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Overview

The encryption module provides functions for encrypting plaintext values (integers) and field elements into PVAC-HFHE ciphertexts. All encryption operations support multi-slot ciphertexts for SIMD-style computation.

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Core encryption functions

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enc_value

Encrypts a single unsigned 64-bit integer into a ciphertext.
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const PubKey&
required
Public key for encryption
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const SecKey&
required
Secret key for generating noise
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uint64_t
required
The plaintext value to encrypt
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Cipher
A ciphertext encrypting the value with depth 0

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Description

Encrypts a single integer value using masking and fusion. The plaintext is split into v + m and -m where m is a random mask, then both parts are encrypted and combined. See: encrypt.hpp:740

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enc_value_depth

Encrypts a single value with a specific noise budget for a given circuit depth.
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const PubKey&
required
Public key for encryption
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const SecKey&
required
Secret key for generating noise
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uint64_t
required
The plaintext value to encrypt
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int
required
Depth hint for noise budget computation
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Cipher
A ciphertext with noise budget allocated for depth d

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Description

Encrypts a value with noise budget planned for a circuit of depth d. Higher depth values allocate more noise entropy for deeper computations. See: encrypt.hpp:732

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enc_values

Encrypts multiple values into a single multi-slot ciphertext.
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const PubKey&
required
Public key for encryption
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const SecKey&
required
Secret key for generating noise
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const std::vector<uint64_t>&
required
Vector of plaintext values to encrypt in parallel slots
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Cipher
A multi-slot ciphertext encrypting all values in parallel

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Description

Creates a ciphertext with multiple slots, each encrypting one value from the input vector. Enables SIMD-style parallel computation on batched data. See: encrypt.hpp:753

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enc_values_depth

Encrypts multiple values with depth-specific noise budget.
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const PubKey&
required
Public key for encryption
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const SecKey&
required
Secret key for generating noise
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const std::vector<uint64_t>&
required
Vector of plaintext values
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int
required
Depth hint for noise allocation
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Cipher
Multi-slot ciphertext with depth d noise budget
See: encrypt.hpp:744

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enc_zero_depth

Encrypts the value zero with a specified noise budget.
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const PubKey&
required
Public key for encryption
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const SecKey&
required
Secret key for generating noise
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int
required
Depth hint for noise budget
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Cipher
Ciphertext encrypting zero

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Description

Generates a zero ciphertext with fresh noise. Used primarily for bootstrapping and recryption operations to refresh noise without changing the encrypted value. See: encrypt.hpp:757

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Field element encryption

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enc_fp_depth

Encrypts a field element with specified depth.
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const PubKey&
required
Public key
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SecKey&
required
Secret key
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const Fp&
required
Field element to encrypt
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int
required
Depth hint
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Cipher
Ciphertext encrypting the field element
See: encrypt.hpp:724

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enc_fp_depth (multi-slot)

Encrypts a vector of field elements.
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const PubKey&
required
Public key
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const SecKey&
required
Secret key
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const std::vector<Fp>&
required
Vector of field elements
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int
required
Depth hint
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Cipher
Multi-slot ciphertext
See: encrypt.hpp:720

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Utility functions

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combine_ciphers

Combines two ciphertexts into a single ciphertext by fusing their layer graphs.
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const PubKey&
required
Public key
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const Cipher&
required
First ciphertext
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const Cipher&
required
Second ciphertext
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Cipher
Fused ciphertext with combined layers and edges

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Description

Merges the layer DAGs and edge sets of two ciphertexts. Layer indices from b are offset appropriately. Used internally during encryption and arithmetic operations.
The function automatically compacts edges if the budget is exceeded.
See: encrypt.hpp:728

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plan_noise

Computes the noise budget allocation for a given depth.
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const PubKey&
required
Public key with parameter set
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int
required
Expected circuit depth
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std::pair<int, int>
Pair of (n2, n3) where n2 is the number of 2-tuples and n3 is the number of 3-tuples to allocate

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Description

Computes the optimal noise budget based on the parameter set’s entropy capacity and the expected circuit depth. The allocation is split between 2-tuples and 3-tuples according to tuple2_fraction. See: encrypt.hpp:643

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sigma_density

Computes the sigma vector density of a ciphertext.
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const PubKey&
required
Public key
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const Cipher&
required
Ciphertext to analyze
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double
Density ratio between 0.0 and 1.0

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Description

Computes the fraction of set bits across all sigma vectors in the ciphertext. A density near 0.5 indicates well-balanced noise. Values far from 0.5 may indicate the need for recryption. See: encrypt.hpp:648

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compact_edges

Compacts the edge set by merging edges with the same layer, index, and sign.
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const PubKey&
required
Public key
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Cipher&
required
Ciphertext to compact (modified in place)

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Description

Reduces the ciphertext size by merging redundant edges. This operation does not change the encrypted value but improves efficiency. See: encrypt.hpp:658

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compact_layers

Removes unused layers from the ciphertext.
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Cipher&
required
Ciphertext to compact (modified in place)

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Description

Removes layers that are not referenced by any edge and updates layer indices accordingly. Reduces memory footprint without affecting the encrypted value. See: encrypt.hpp:662