FHE.Sol - Fhenix Documentation

Overview

The FHE library provides a comprehensive set of functions for working with Fully Homomorphic Encryption (FHE) in Solidity smart contracts. This library enables you to perform computations on encrypted data without decrypting it, ensuring privacy throughout your contract’s execution.

All functions in the FHE library are prefixed with FHE. when called. For example: FHE.add(a, b) or FHE.allowPublic(value).

Encrypted Data Types

The library supports the following encrypted data types:

Type	Description
`ebool`	Encrypted boolean value
`euint8`	Encrypted 8-bit unsigned integer
`euint16`	Encrypted 16-bit unsigned integer
`euint32`	Encrypted 32-bit unsigned integer
`euint64`	Encrypted 64-bit unsigned integer
`euint128`	Encrypted 128-bit unsigned integer
`eaddress`	Encrypted Ethereum address

Type Conversion

From Plaintext to Encrypted Types

asEbool

bool

required

Plaintext boolean value to encrypt

int32

Optional security zone identifier for isolating encrypted computations

ebool

Encrypted boolean value

Converts a plaintext boolean value to an encrypted boolean.

ebool encrypted = FHE.asEbool(true);
ebool encryptedWithZone = FHE.asEbool(true, 1);

asEuint8

uint256

required

Plaintext value to encrypt (must fit in 8 bits)

int32

Optional security zone identifier

euint8

Encrypted 8-bit unsigned integer

Converts a plaintext value to an encrypted 8-bit unsigned integer.

euint8 encrypted = FHE.asEuint8(42);

asEuint16

uint256

required

Plaintext value to encrypt (must fit in 16 bits)

int32

Optional security zone identifier

euint16

Encrypted 16-bit unsigned integer

Converts a plaintext value to an encrypted 16-bit unsigned integer.

euint16 encrypted = FHE.asEuint16(1000);

asEuint32

uint256

required

Plaintext value to encrypt (must fit in 32 bits)

int32

Optional security zone identifier

euint32

Encrypted 32-bit unsigned integer

Converts a plaintext value to an encrypted 32-bit unsigned integer.

euint32 encrypted = FHE.asEuint32(50000);

asEuint64

uint256

required

Plaintext value to encrypt (must fit in 64 bits)

int32

Optional security zone identifier

euint64

Encrypted 64-bit unsigned integer

Converts a plaintext value to an encrypted 64-bit unsigned integer.

euint64 encrypted = FHE.asEuint64(1000000000);

asEuint128

uint256

required

Plaintext value to encrypt (must fit in 128 bits)

int32

Optional security zone identifier

euint128

Encrypted 128-bit unsigned integer

Converts a plaintext value to an encrypted 128-bit unsigned integer.

euint128 encrypted = FHE.asEuint128(1000000000000000000);

asEaddress

address

required

Plaintext Ethereum address to encrypt

int32

Optional security zone identifier

eaddress

Encrypted Ethereum address

Converts a plaintext address value to an encrypted address.

eaddress encrypted = FHE.asEaddress(0x1234567890123456789012345678901234567890);

From Encrypted Input Structures

asEbool (from InEbool)

InEbool

required

Encrypted input structure containing boolean data

ebool

Encrypted boolean value

Converts an encrypted input structure to an encrypted boolean.

ebool encrypted = FHE.asEbool(encryptedInput);

asEuint8 (from InEuint8)

InEuint8

required

Encrypted input structure containing 8-bit integer data

euint8

Encrypted 8-bit unsigned integer

Converts an encrypted input structure to an encrypted 8-bit unsigned integer.

euint8 encrypted = FHE.asEuint8(encryptedInput);

asEuint16 (from InEuint16)

InEuint16

required

Encrypted input structure containing 16-bit integer data

euint16

Encrypted 16-bit unsigned integer

Converts an encrypted input structure to an encrypted 16-bit unsigned integer.

euint16 encrypted = FHE.asEuint16(encryptedInput);

asEuint32 (from InEuint32)

InEuint32

required

Encrypted input structure containing 32-bit integer data

euint32

Encrypted 32-bit unsigned integer

Converts an encrypted input structure to an encrypted 32-bit unsigned integer.

euint32 encrypted = FHE.asEuint32(encryptedInput);

asEuint64 (from InEuint64)

InEuint64

required

Encrypted input structure containing 64-bit integer data

euint64

Encrypted 64-bit unsigned integer

Converts an encrypted input structure to an encrypted 64-bit unsigned integer.

euint64 encrypted = FHE.asEuint64(encryptedInput);

asEuint128 (from InEuint128)

InEuint128

required

Encrypted input structure containing 128-bit integer data

euint128

Encrypted 128-bit unsigned integer

Converts an encrypted input structure to an encrypted 128-bit unsigned integer.

euint128 encrypted = FHE.asEuint128(encryptedInput);

asEaddress (from InEaddress)

InEaddress

required

Encrypted input structure containing address data

eaddress

Encrypted Ethereum address

Converts an encrypted input structure to an encrypted address.

eaddress encrypted = FHE.asEaddress(encryptedInput);

Type Conversion Between Encrypted Types

asEbool (from euint)

Converts various encrypted integer types to an encrypted boolean.

ebool result = FHE.asEbool(euint8Value);
ebool result = FHE.asEbool(euint16Value);
ebool result = FHE.asEbool(euint32Value);
ebool result = FHE.asEbool(euint64Value);
ebool result = FHE.asEbool(euint128Value);
ebool result = FHE.asEbool(eaddressValue);

asEuint8 (from other encrypted types)

Converts various encrypted types to an encrypted 8-bit unsigned integer.

euint8 result = FHE.asEuint8(eboolValue);
euint8 result = FHE.asEuint8(euint16Value);
euint8 result = FHE.asEuint8(euint32Value);
euint8 result = FHE.asEuint8(euint64Value);
euint8 result = FHE.asEuint8(euint128Value);
euint8 result = FHE.asEuint8(eaddressValue);

asEuint16 (from other encrypted types)

Converts various encrypted types to an encrypted 16-bit unsigned integer.

euint16 result = FHE.asEuint16(eboolValue);
euint16 result = FHE.asEuint16(euint8Value);
euint16 result = FHE.asEuint16(euint32Value);
euint16 result = FHE.asEuint16(euint64Value);
euint16 result = FHE.asEuint16(euint128Value);
euint16 result = FHE.asEuint16(eaddressValue);

asEuint32 (from other encrypted types)

Converts various encrypted types to an encrypted 32-bit unsigned integer.

euint32 result = FHE.asEuint32(eboolValue);
euint32 result = FHE.asEuint32(euint8Value);
euint32 result = FHE.asEuint32(euint16Value);
euint32 result = FHE.asEuint32(euint64Value);
euint32 result = FHE.asEuint32(euint128Value);
euint32 result = FHE.asEuint32(eaddressValue);

asEuint64 (from other encrypted types)

Converts various encrypted types to an encrypted 64-bit unsigned integer.

euint64 result = FHE.asEuint64(eboolValue);
euint64 result = FHE.asEuint64(euint8Value);
euint64 result = FHE.asEuint64(euint16Value);
euint64 result = FHE.asEuint64(euint32Value);
euint64 result = FHE.asEuint64(euint128Value);
euint64 result = FHE.asEuint64(eaddressValue);

asEuint128 (from other encrypted types)

Converts various encrypted types to an encrypted 128-bit unsigned integer.

euint128 result = FHE.asEuint128(eboolValue);
euint128 result = FHE.asEuint128(euint8Value);
euint128 result = FHE.asEuint128(euint16Value);
euint128 result = FHE.asEuint128(euint32Value);
euint128 result = FHE.asEuint128(euint64Value);
euint128 result = FHE.asEuint128(eaddressValue);

asEaddress (from euint128)

Converts an encrypted 128-bit unsigned integer to an encrypted address.

eaddress result = FHE.asEaddress(euint128Value);

Arithmetic Operations

add

Performs addition of two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Sum of the two encrypted values

euint8 sum = FHE.add(a, b);
euint32 sum = FHE.add(x, y);

sub

Performs subtraction of two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Difference of the two encrypted values

euint8 diff = FHE.sub(a, b);
euint32 diff = FHE.sub(x, y);

mul

Performs multiplication of two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Product of the two encrypted values

euint8 product = FHE.mul(a, b);
euint32 product = FHE.mul(x, y);

div

Performs division of two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value (dividend)

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (divisor, must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Quotient of the division

Division by zero will cause the operation to revert. Ensure the divisor is non-zero.

euint8 quotient = FHE.div(a, b);
euint32 quotient = FHE.div(x, y);

rem

Calculates the remainder when dividing two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value (dividend)

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (divisor, must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Remainder of the division

euint8 remainder = FHE.rem(a, b);
euint32 remainder = FHE.rem(x, y);

square

Calculates the square of an encrypted unsigned integer.

euint8 | euint16 | euint32 | euint64 | euint128

required

Encrypted value to square

euint8 | euint16 | euint32 | euint64 | euint128

Square of the encrypted value

euint8 squared = FHE.square(a);
euint32 squared = FHE.square(x);

Bitwise Operations

and

Performs a bitwise AND operation on two encrypted values.

required

Left-hand side encrypted value

required

Right-hand side encrypted value (must match lhs type)

Result of the bitwise AND operation

ebool result = FHE.and(a, b);
euint8 result = FHE.and(x, y);

or

Performs a bitwise OR operation on two encrypted values.

required

Left-hand side encrypted value

required

Right-hand side encrypted value (must match lhs type)

Result of the bitwise OR operation

ebool result = FHE.or(a, b);
euint8 result = FHE.or(x, y);

xor

Performs a bitwise XOR operation on two encrypted values.

required

Left-hand side encrypted value

required

Right-hand side encrypted value (must match lhs type)

Result of the bitwise XOR operation

ebool result = FHE.xor(a, b);
euint8 result = FHE.xor(x, y);

not

Performs a bitwise NOT operation on an encrypted value.

required

Encrypted value to negate

Result of the bitwise NOT operation

ebool result = FHE.not(a);
euint8 result = FHE.not(x);

shl

Performs a shift left operation on an encrypted unsigned integer.

euint8 | euint16 | euint32 | euint64 | euint128

required

Encrypted value to shift

euint8 | euint16 | euint32 | euint64 | euint128

required

Number of bits to shift left (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Result of the shift left operation

euint8 result = FHE.shl(value, shiftAmount);
euint32 result = FHE.shl(x, y);

shr

Performs a shift right operation on an encrypted unsigned integer.

euint8 | euint16 | euint32 | euint64 | euint128

required

Encrypted value to shift

euint8 | euint16 | euint32 | euint64 | euint128

required

Number of bits to shift right (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Result of the shift right operation

euint8 result = FHE.shr(value, shiftAmount);
euint32 result = FHE.shr(x, y);

rol

Performs a rotate left operation on an encrypted unsigned integer.

euint8 | euint16 | euint32 | euint64 | euint128

required

Encrypted value to rotate

euint8 | euint16 | euint32 | euint64 | euint128

required

Number of bits to rotate left (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Result of the rotate left operation

euint8 result = FHE.rol(value, rotateAmount);
euint32 result = FHE.rol(x, y);

ror

Performs a rotate right operation on an encrypted unsigned integer.

euint8 | euint16 | euint32 | euint64 | euint128

required

Encrypted value to rotate

euint8 | euint16 | euint32 | euint64 | euint128

required

Number of bits to rotate right (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

Result of the rotate right operation

euint8 result = FHE.ror(value, rotateAmount);
euint32 result = FHE.ror(x, y);

Comparison Operations

eq

Checks if two encrypted values are equal and returns an encrypted boolean.

required

Left-hand side encrypted value

required

Right-hand side encrypted value (must match lhs type)

ebool

Encrypted boolean indicating equality

ebool isEqual = FHE.eq(a, b);
ebool isEqual = FHE.eq(address1, address2);

ne

Checks if two encrypted values are not equal and returns an encrypted boolean.

required

Left-hand side encrypted value

required

Right-hand side encrypted value (must match lhs type)

ebool

Encrypted boolean indicating inequality

ebool isNotEqual = FHE.ne(a, b);
ebool isNotEqual = FHE.ne(address1, address2);

lt

Checks if the first encrypted unsigned integer is less than the second and returns an encrypted boolean.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

ebool

Encrypted boolean indicating if lhs is less than rhs

ebool isLessThan = FHE.lt(a, b);
ebool isLessThan = FHE.lt(x, y);

lte

Checks if the first encrypted unsigned integer is less than or equal to the second and returns an encrypted boolean.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

ebool

Encrypted boolean indicating if lhs is less than or equal to rhs

ebool isLessEqual = FHE.lte(a, b);
ebool isLessEqual = FHE.lte(x, y);

gt

Checks if the first encrypted unsigned integer is greater than the second and returns an encrypted boolean.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

ebool

Encrypted boolean indicating if lhs is greater than rhs

ebool isGreaterThan = FHE.gt(a, b);
ebool isGreaterThan = FHE.gt(x, y);

gte

Checks if the first encrypted unsigned integer is greater than or equal to the second and returns an encrypted boolean.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

ebool

Encrypted boolean indicating if lhs is greater than or equal to rhs

ebool isGreaterEqual = FHE.gte(a, b);
ebool isGreaterEqual = FHE.gte(x, y);

Min/Max Functions

min

Returns the smaller of two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

The smaller of the two encrypted values

euint8 minimum = FHE.min(a, b);
euint32 minimum = FHE.min(x, y);

max

Returns the larger of two encrypted unsigned integers.

euint8 | euint16 | euint32 | euint64 | euint128

required

Left-hand side encrypted value

euint8 | euint16 | euint32 | euint64 | euint128

required

Right-hand side encrypted value (must match lhs type)

euint8 | euint16 | euint32 | euint64 | euint128

The larger of the two encrypted values

euint8 maximum = FHE.max(a, b);
euint32 maximum = FHE.max(x, y);

Control Flow

select

Conditionally selects between two encrypted values based on an encrypted boolean condition.

ebool

required

Encrypted boolean condition

required

Value to return if condition is true

required

Value to return if condition is false (must match ifTrue type)

Selected value based on condition

Use select instead of if/else statements when working with encrypted values. Conditional branching doesn’t work with encrypted data.

euint8 result = FHE.select(condition, a, b);
ebool result = FHE.select(condition, trueValue, falseValue);
eaddress result = FHE.select(condition, address1, address2);

Decryption Results

getDecryptResult

Retrieves a published decryption result. This function should be called after a result has been published via publishDecryptResult.

uint256

required

Hash of the encrypted value that was previously decrypted

uint256

Decrypted result value

This function will revert if the decryption result is not available yet. Use getDecryptResultSafe for non-reverting behavior.

uint256 result = FHE.getDecryptResult(ctHash);

getDecryptResultSafe

Safely retrieves the decrypted result of a previously decrypted value. Unlike getDecryptResult, this function returns a boolean flag indicating whether the decryption is complete.

uint256

required

Hash of the encrypted value that was previously decrypted

uint256

Decrypted result value (valid only if decrypted is true)

bool

Boolean indicating whether the decryption has completed successfully

(uint256 result, bool decrypted) = FHE.getDecryptResultSafe(ctHash);
if (decrypted) {
    // Use result
}

Decrypt Result Publishing & Verification

publishDecryptResult

Publishes a signed decrypt result from the Threshold Network to the chain. The TaskManager verifies the ECDSA signature before storing the result. Anyone holding a valid signature can call this.

required

The ciphertext hash to publish a result for

required

The decrypted plaintext value (type matches the ctHash type)

bytes

required

The ECDSA signature from the Threshold Network’s Dispatcher

// Publish a decrypt result for a euint64
FHE.publishDecryptResult(myEncryptedValue, uint64(42), signature);

// Publish for an ebool
FHE.publishDecryptResult(myEncryptedBool, true, signature);

verifyDecryptResult

Verifies a decrypt result signature without publishing. Reverts if the signature is invalid.

required

The ciphertext hash

required

The decrypted plaintext value

bytes

required

The ECDSA signature to verify

bool

Returns true if the signature is valid. Reverts otherwise.

bool valid = FHE.verifyDecryptResult(myEncryptedValue, uint64(42), signature);

publishDecryptResultBatch

Publishes multiple signed decrypt results in a single transaction for gas efficiency.

uint256[]

required

Array of ciphertext hashes

uint256[]

required

Array of decrypted plaintext values

bytes[]

required

Array of ECDSA signatures (one per result)

FHE.publishDecryptResultBatch(ctHashes, results, signatures);

verifyDecryptResultSafe

Same as verifyDecryptResult, but returns false instead of reverting on invalid signatures.

required

The ciphertext hash

required

The decrypted plaintext value

bytes

required

The ECDSA signature to verify

bool

Returns true if valid, false if invalid (never reverts on bad signature)

bool valid = FHE.verifyDecryptResultSafe(myEncryptedValue, uint64(42), signature);
if (!valid) {
    revert("Invalid decrypt result signature");
}

verifyDecryptResultSafe

Like verifyDecryptResult, but returns false instead of reverting if the signature is invalid.

required

Ciphertext handle of the encrypted value

required

The decrypted plaintext value

bytes

required

The Threshold Network signature

bool

True if the signature is valid, false otherwise (does not revert)

bool valid = FHE.verifyDecryptResultSafe(encryptedAmount, amount, signature);
if (valid) {
    // proceed with verified plaintext
}

publishDecryptResultBatch

Publishes multiple decrypted results on-chain in a single call. Each element is verified independently.

required

Array of ciphertext handles

required

Array of decrypted plaintext values (must match ctHashes length and type)

bytes[]

required

Array of Threshold Network signatures (must match ctHashes length)

euint64[] memory handles = new euint64[](2);
handles[0] = encryptedBid1;
handles[1] = encryptedBid2;

uint64[] memory values = new uint64[](2);
values[0] = bid1Plaintext;
values[1] = bid2Plaintext;

bytes[] memory sigs = new bytes[](2);
sigs[0] = sig1;
sigs[1] = sig2;

FHE.publishDecryptResultBatch(handles, values, sigs);

verifyDecryptResultBatch

Verifies multiple Threshold Network signatures in a single call without storing results. Reverts if any signature is invalid.

required

Array of ciphertext handles

required

Array of decrypted plaintext values

bytes[]

required

Array of Threshold Network signatures

bool

True if all signatures are valid (reverts otherwise)

bool allValid = FHE.verifyDecryptResultBatch(handles, values, sigs);

verifyDecryptResultBatchSafe

Like verifyDecryptResultBatch, but returns a bool[] indicating which entries are valid instead of reverting.

required

Array of ciphertext handles

required

Array of decrypted plaintext values

bytes[]

required

Array of Threshold Network signatures

bool[]

Array of booleans — true for each valid signature, false for invalid

bool[] memory results = FHE.verifyDecryptResultBatchSafe(handles, values, sigs);
for (uint i = 0; i < results.length; i++) {
    if (results[i]) {
        // entry i is valid
    }
}

Access Control

allow

Grants permission to the specified account to access the encrypted value.

required

Encrypted value to grant access to

address

required

Address of the account to grant access to

FHE.allow(encryptedValue, userAddress);

allowThis

Grants permission to the current contract to access the encrypted value.

required

Encrypted value to grant access to

Call allowThis after modifying encrypted values if you need to access them later in the same contract.

euint32 counter = FHE.add(counter, FHE.asEuint32(1));
FHE.allowThis(counter);  // Required for future access

allowPublic

Grants public permission to access the encrypted value. Once called, anyone can request decryption of this value off-chain via decryptForTx without needing a permit.

required

Encrypted value to grant public access to

Once allowPublic is called, the value can be decrypted by anyone. Only use this when you intend to reveal the value publicly (e.g., after an auction closes or when unwrapping tokens).

// Allow anyone to decrypt the winning bid after auction closes
FHE.allowPublic(highestBid);
FHE.allowPublic(highestBidder);

// Now anyone can call decryptForTx off-chain without a permit

allowSender

Grants permission to the message sender to access the encrypted value.

required

Encrypted value to grant access to

FHE.allowSender(encryptedValue);

allowTransient

Grants temporary permission to the specified account to access the encrypted value.

required

Encrypted value to grant access to

address

required

Address of the account to grant temporary access to

FHE.allowTransient(encryptedValue, userAddress);

isAllowed

Checks if the specified account has permission to access the encrypted value.

required

Encrypted value to check access for

address

required

Address of the account to check

bool

True if the account has permission, false otherwise

bool hasAccess = FHE.isAllowed(encryptedValue, userAddress);

isPubliclyAllowed

Checks if the encrypted value has been granted public access via allowPublic.

required

Encrypted value to check

bool

True if the value is publicly accessible, false otherwise

bool isPublic = FHE.isPubliclyAllowed(encryptedValue);

Utility Functions

isInitialized

Checks whether an encrypted value has been initialized (i.e., is not a zero/empty handle).

required

Encrypted value to check

bool

True if the value has been initialized, false otherwise

if (FHE.isInitialized(encryptedBalance)) {
    // safe to use
}

unwrap

Extracts the raw bytes32 handle from a typed encrypted value.

required

Encrypted value to unwrap

bytes32

The underlying ciphertext handle

bytes32 handle = FHE.unwrap(encryptedValue);

wrapEbool / wrapEuint8 / wrapEuint16 / wrapEuint32 / wrapEuint64 / wrapEuint128 / wrapEaddress

Wraps a raw bytes32 handle into a typed encrypted value. Use this when you have a raw handle (e.g., from storage or an event) and need to convert it to a typed encrypted value.

bytes32

required

Raw ciphertext handle to wrap

ebool val = FHE.wrapEbool(handle);
euint8 val = FHE.wrapEuint8(handle);
euint16 val = FHE.wrapEuint16(handle);
euint32 val = FHE.wrapEuint32(handle);
euint64 val = FHE.wrapEuint64(handle);
euint128 val = FHE.wrapEuint128(handle);
eaddress val = FHE.wrapEaddress(handle);

Bindings

The FHE library provides binding libraries that enable syntactic sugar for working with encrypted types. These bindings allow for more intuitive and object-oriented usage patterns.

Using Bindings

With bindings, you can use encrypted types with dot notation instead of calling FHE.* functions:

// Without bindings
euint8 sum = FHE.add(a, b);

// With bindings
euint8 sum = a.add(b);

Each encrypted type has a corresponding binding library that includes all the operations available for that type.

Example with Bindings

// Use secure encrypted input
InEuint8 encryptedInputA;  // Provided by client-side encryption
InEuint8 encryptedInputB;    // Provided by client-side encryption

euint8 a = FHE.asEuint8(encryptedInputA);
euint8 b = FHE.asEuint8(encryptedInputB);

// Arithmetic operations
euint8 sum = a.add(b);        // Addition
euint8 diff = a.sub(b);       // Subtraction
euint8 product = a.mul(b);    // Multiplication
euint8 quotient = a.div(b);   // Division
euint8 remainder = a.rem(b);  // Remainder
euint8 squared = a.square();  // Square

// Bitwise operations
euint8 bitwiseAnd = a.and(b);   // AND
euint8 bitwiseOr = a.or(b);     // OR
euint8 bitwiseXor = a.xor(b);   // XOR
euint8 bitwiseNot = a.not();    // NOT
euint8 shiftLeft = a.shl(b);    // Shift Left
euint8 shiftRight = a.shr(b);   // Shift Right
euint8 rotateLeft = a.rol(b);    // Rotate Left
euint8 rotateRight = a.ror(b);  // Rotate Right

// Comparison operations
ebool isEqual = a.eq(b);          // Equal
ebool isNotEqual = a.ne(b);        // Not Equal
ebool isLessThan = a.lt(b);       // Less Than
ebool isLessEqual = a.lte(b);     // Less Than or Equal
ebool isGreaterThan = a.gt(b);    // Greater Than
ebool isGreaterEqual = a.gte(b);  // Greater Than or Equal

// Min/Max functions
euint8 minimum = a.min(b);  // Minimum
euint8 maximum = a.max(b);  // Maximum

// Type conversion
ebool converted = a.toBool();    // Convert to ebool
euint16 toU16 = a.toU16();       // Convert to euint16
euint32 toU32 = a.toU32();       // Convert to euint32
euint64 toU64 = a.toU64();       // Convert to euint64
euint128 toU128 = a.toU128();    // Convert to euint128

// Utility
bool initialized = a.isInitialized();          // Check if initialized
bytes32 handle = a.unwrap();                   // Get raw handle

// Access control
a.allow(address);                       // Allow access
a.allowThis();                          // Allow this contract
a.allowPublic();                        // Allow public access
a.allowSender();                        // Allow sender
a.allowTransient(address);              // Allow transient access
bool hasAccess = a.isAllowed(address);  // Check access

Security Considerations

Always consider security implications when working with encrypted data.

Initialization: All FHE functions check if their inputs are initialized and set them to 0 if not.
Decryption: Decryption is a two-phase process — mark values with allowPublic on-chain, decrypt off-chain via the Client SDK, then publish/verify the result with publishDecryptResult or verifyDecryptResult. Only reveal values when absolutely necessary.
Security Zones: Some functions accept a securityZone parameter to isolate different encrypted computations. FHE operations can only be performed between ciphertexts that share the same security zone.
Access Control: The library provides fine-grained access control through the allow* functions. Always set proper permissions before accessing encrypted values.
Type Safety: Ensure encrypted values use compatible types when performing operations. Type mismatches will cause errors.

Example Usage

Basic Example

This example shows how to perform private computations while keeping all intermediate values encrypted:

// Use secure encrypted input
InEuint8 encryptedInputA;  // Provided by client-side encryption
InEuint8 encryptedInputB;  // Provided by client-side encryption

euint8 a = FHE.asEuint8(encryptedInputA);
euint8 b = FHE.asEuint8(encryptedInputB);

// Perform operations
euint8 sum = FHE.add(a, b);           // Encrypted addition
euint8 product = FHE.mul(a, b);      // Encrypted multiplication
ebool isGreater = FHE.gt(b, a);      // Encrypted comparison

// Conditional logic
euint8 result = FHE.select(isGreater, sum, product);

// Grant access for future use and allow public decryption
FHE.allowThis(result);
FHE.allowPublic(result);

// Off-chain: client calls decryptForTx(ctHash) to get plaintext + signature
// On-chain: publish the verified result
// FHE.publishDecryptResult(result, plaintext, signature);

Example with Bindings

// Use secure encrypted input
InEuint8 encryptedInputA;  // Provided by client-side encryption
InEuint8 encryptedInputB;  // Provided by client-side encryption

euint8 a = FHE.asEuint8(encryptedInputA);
euint8 b = FHE.asEuint8(encryptedInputB);

// Perform operations using dot notation
euint8 sum = a.add(b);               // Encrypted addition
euint8 product = a.mul(b);           // Encrypted multiplication
ebool isGreater = b.gt(a);           // Encrypted comparison

// Conditional logic
euint8 result = isGreater.select(sum, product);

// Grant access for future use and allow public decryption
result.allowThis();
result.allowPublic();

Next Steps

Learn about encrypted data types and their use cases
Explore encrypted operations in detail
Review access control mechanisms for managing permissions
Check out best practices for secure FHE development

​Overview

​Encrypted Data Types

​Type Conversion

​From Plaintext to Encrypted Types

​asEbool

​asEuint8

​asEuint16

​asEuint32

​asEuint64

​asEuint128

​asEaddress

​From Encrypted Input Structures

​asEbool (from InEbool)

​asEuint8 (from InEuint8)

​asEuint16 (from InEuint16)

​asEuint32 (from InEuint32)

​asEuint64 (from InEuint64)

​asEuint128 (from InEuint128)

​asEaddress (from InEaddress)

​Type Conversion Between Encrypted Types

​asEbool (from euint)

​asEuint8 (from other encrypted types)

​asEuint16 (from other encrypted types)

​asEuint32 (from other encrypted types)

​asEuint64 (from other encrypted types)

​asEuint128 (from other encrypted types)

​asEaddress (from euint128)

​Arithmetic Operations

​add

​sub

​mul

​div

​rem

​square

​Bitwise Operations

​and

​or

​xor

​not

​shl

​shr

​rol

​ror

​Comparison Operations

​eq

​ne

​lt

​lte

​gt

​gte

​Min/Max Functions

​min

​max

​Control Flow

​select

​Decryption Results

​getDecryptResult

​getDecryptResultSafe

​Decrypt Result Publishing & Verification

​publishDecryptResult

​verifyDecryptResult

​publishDecryptResultBatch

​verifyDecryptResultSafe

​verifyDecryptResultSafe

​publishDecryptResultBatch

​verifyDecryptResultBatch

​verifyDecryptResultBatchSafe

​Access Control

​allow

​allowThis

​allowPublic

​allowSender

​allowTransient

​isAllowed

​isPubliclyAllowed

​Utility Functions

​isInitialized

​unwrap

​wrapEbool / wrapEuint8 / wrapEuint16 / wrapEuint32 / wrapEuint64 / wrapEuint128 / wrapEaddress

​Bindings

Overview

Encrypted Data Types

Type Conversion

From Plaintext to Encrypted Types

asEbool

asEuint8

asEuint16

asEuint32

asEuint64

asEuint128

asEaddress

From Encrypted Input Structures

asEbool (from InEbool)

asEuint8 (from InEuint8)

asEuint16 (from InEuint16)

asEuint32 (from InEuint32)

asEuint64 (from InEuint64)

asEuint128 (from InEuint128)

asEaddress (from InEaddress)

Type Conversion Between Encrypted Types

asEbool (from euint)

asEuint8 (from other encrypted types)

asEuint16 (from other encrypted types)

asEuint32 (from other encrypted types)

asEuint64 (from other encrypted types)

asEuint128 (from other encrypted types)

asEaddress (from euint128)

Arithmetic Operations

add

sub

mul

div

rem

square

Bitwise Operations

and

or

xor

not

shl

shr

rol

ror

Comparison Operations

eq

ne

lt

lte

gt

gte

Min/Max Functions

min

max

Control Flow

select

Decryption Results

getDecryptResult

getDecryptResultSafe

Decrypt Result Publishing & Verification

publishDecryptResult

verifyDecryptResult

publishDecryptResultBatch

verifyDecryptResultSafe

verifyDecryptResultSafe

publishDecryptResultBatch

verifyDecryptResultBatch

verifyDecryptResultBatchSafe

Access Control

allow

allowThis

allowPublic

allowSender

allowTransient

isAllowed

isPubliclyAllowed

Utility Functions

isInitialized

unwrap

wrapEbool / wrapEuint8 / wrapEuint16 / wrapEuint32 / wrapEuint64 / wrapEuint128 / wrapEaddress

Bindings