rotate

Fixed Rotation Key-Based Rotation

Engine.rotate(ciphertext, fixed_rotation_key)
Rotates the input ciphertext to the left by the delta value specified in the fixed rotation key. For example, rotating [1, 2, 3, 4] by 1 results in [2, 3, 4, 1]. In general, does not consume any level. A level is consumed only if the engine is not configured for bootstrapping and the ciphertext is at the maximum allowable level for a given parameter.
  • Input:
    • Ciphertext
    • FixedRotationKey
  • Output:
    • Ciphertext

Warning

  • The matrix form does not support this operation.
from desilofhe import Engine

engine = Engine()
secret_key = engine.create_secret_key()
public_key = engine.create_public_key(secret_key)
fixed_rotation_key = engine.create_fixed_rotation_key(secret_key, delta=1)

message = [1, 2, 3]
ciphertext = engine.encrypt(message, public_key)
rotated_ciphertext = engine.rotate(ciphertext, fixed_rotation_key)

Fixed rotation keys only allow rotation by a specific delta value. If you need various rotations, using multiple rotations with fixed rotation key of delta 1 is less efficient than employing general rotation keys. However, if a specific rotation is frequently performed, generating a fixed rotation key for that value is more optimal.

Rotation Key-Based Rotation

Engine.rotate(ciphertext, rotation_key, delta)
Rotates the input ciphertext to the left by the specified delta value. For example, rotating [1, 2, 3, 4] by 1 results in [2, 3, 4, 1]. In general, does not consume any level. A level is consumed only if the engine is not configured for bootstrapping and the ciphertext is at the maximum allowable level for a given parameter.
  • Input:
    • Ciphertext
    • RotationKey
    • delta: int
  • Output:
    • Ciphertext

Warning

  • The matrix form does not support this operation.
from desilofhe import Engine

engine = Engine()
secret_key = engine.create_secret_key()
public_key = engine.create_public_key(secret_key)
rotation_key = engine.create_rotation_key(secret_key)

message = [1, 2, 3]
ciphertext = engine.encrypt(message, public_key)
rotated_ciphertext = engine.rotate(ciphertext, rotation_key, delta=1)

Rotation keys are constructed using a set of fixed rotation keys with \(2^n\) deltas. When rotating with a delta that is not a power of 2, multiple rotations each with a power of two delta are done internally. If many different rotations are needed, general rotation keys are more efficient. For frequent rotations by specific deltas, generating a fixed rotation key for that value is more optimal.

Bootstrap Key-Based Rotation

Engine.rotate(ciphertext, bootstrap_key, delta)
Rotates the input ciphertext to the left by the specified delta value, using the fixed roll keys contained in the bootstrap key. For example, rotating [1, 2, 3, 4] by 1 results in [2, 3, 4, 1]. The engine must be created with Engine(bootstrap=True).
  • Input:
    • Ciphertext
    • BootstrapKey
    • delta: int
  • Output:
    • Ciphertext

Warning

  • The matrix form does not support this operation.
from desilofhe import Engine

engine = Engine(bootstrap=True)
secret_key = engine.create_secret_key()
bootstrap_key = engine.create_bootstrap_key(secret_key)

message = [1, 2, 3]
ciphertext = engine.encrypt(message, secret_key)
rotated_ciphertext = engine.rotate(ciphertext, bootstrap_key, delta=1)

Evaluation Key-Based Rotation

Engine.rotate(ciphertext, evaluation_key, delta)
Rotates the input ciphertext to the left by the specified delta value, using the keys bundled in the evaluation key. For example, rotating [1, 2, 3, 4] by 1 results in [2, 3, 4, 1]. In general, does not consume any level. A level is consumed only if the engine is not configured for bootstrapping and the ciphertext is at the maximum allowable level for a given parameter.
  • Input:
    • Ciphertext
    • EvaluationKey
    • delta: int
  • Output:
    • Ciphertext

Warning

  • The matrix form does not support this operation.
from desilofhe import Engine

engine = Engine()
secret_key = engine.create_secret_key()
evaluation_key = engine.create_evaluation_key(secret_key)

message = [1, 2, 3]
ciphertext = engine.encrypt(message, secret_key)
rotated_ciphertext = engine.rotate(ciphertext, evaluation_key, delta=1)

Plaintext Rotation

Engine.rotate(plaintext, delta)
Rotates the input plaintext to the left by the specified delta value. For example, rotating [1, 2, 3, 4] by 1 results in [2, 3, 4, 1].

Warning

  • The matrix form does not support this operation.
  • Input:
    • Plaintext
    • delta: int
  • Output:
    • Plaintext
from desilofhe import Engine

engine = Engine()

message = [1, 2, 3]
plaintext = engine.encode(message)
rotated_plaintext = engine.rotate(plaintext, delta=1)