category

`authenticated_channel`

Identity-authenticated ephemeral X25519 channels with directional XChaCha20-Poly1305 keys, strict counters, and per-message symmetric key ratcheting.

Availability:

logtalk_load(crypto(loader))

Author: Paulo Moura
Version: 1:0:0
Date: 2026-08-03

Compilation flags:

static

Complements:

crypto

Uses:

list
sha256
type

Remarks:

(none)

Inherited public predicates:

(none)

Public predicates 

`authenticated_channel_initiate/4`

Creates a signed ephemeral-key Offer and PendingState for an initiator using IdentitySeed and the pinned ResponderIdentityPublicKey.

Compilation flags:

static

Template:

authenticated_channel_initiate(IdentitySeed,ResponderIdentityPublicKey,Offer,PendingState)

Mode and number of proofs:

authenticated_channel_initiate(+list(byte),+list(byte),-compound,-compound) - one_or_error

Exceptions:

IdentitySeed is a partial list or a list with an element which is a variable:

instantiation_error

IdentitySeed is neither a variable nor a list of 32 bytes:

type_error(list(byte,32),IdentitySeed)

IdentitySeed contains a non-integer byte:

type_error(integer,Byte)

IdentitySeed contains an integer outside the byte range:

domain_error(byte,Byte)

ResponderIdentityPublicKey is a partial list or a list with an element which is a variable:

instantiation_error

ResponderIdentityPublicKey is neither a variable nor a list of 32 bytes:

type_error(list(byte,32),ResponderIdentityPublicKey)

ResponderIdentityPublicKey contains a non-integer byte:

type_error(integer,Byte)

ResponderIdentityPublicKey contains an integer outside the byte range:

domain_error(byte,Byte)

`authenticated_channel_accept/5`

Verifies Offer against the pinned InitiatorIdentityPublicKey, creates a signed Response, and returns the responder Channel state.

Compilation flags:

static

Template:

authenticated_channel_accept(IdentitySeed,InitiatorIdentityPublicKey,Offer,Response,Channel)

Mode and number of proofs:

authenticated_channel_accept(+list(byte),+list(byte),+compound,-compound,-compound) - zero_or_one_or_error

Exceptions:

IdentitySeed is a partial list or a list with an element which is a variable:

instantiation_error

IdentitySeed is neither a variable nor a list of 32 bytes:

type_error(list(byte,32),IdentitySeed)

IdentitySeed contains a non-integer byte:

type_error(integer,Byte)

IdentitySeed contains an integer outside the byte range:

domain_error(byte,Byte)

InitiatorIdentityPublicKey is a partial list or a list with an element which is a variable:

instantiation_error

InitiatorIdentityPublicKey is neither a variable nor a list of 32 bytes:

type_error(list(byte,32),InitiatorIdentityPublicKey)

InitiatorIdentityPublicKey contains a non-integer byte:

type_error(integer,Byte)

InitiatorIdentityPublicKey contains an integer outside the byte range:

domain_error(byte,Byte)

Offer is a variable or contains a partial byte list or a byte list with an element which is a variable:

instantiation_error

Offer is neither a variable nor a compound term:

type_error(compound,Offer)

Offer is not a valid authenticated channel offer term:

domain_error(authenticated_channel_offer,Offer)

Offer contains a key field which is not a list of 32 bytes:

type_error(list(byte,32),Bytes)

Offer contains a signature field which is not a list of 64 bytes:

type_error(list(byte,64),Signature)

Offer contains a non-integer byte:

type_error(integer,Byte)

Offer contains an integer outside the byte range:

domain_error(byte,Byte)

`authenticated_channel_finalize/3`

Verifies Response against the identity pinned in PendingState and returns the initiator Channel state.

Compilation flags:

static

Template:

authenticated_channel_finalize(PendingState,Response,Channel)

Mode and number of proofs:

authenticated_channel_finalize(+compound,+compound,-compound) - zero_or_one_or_error

Exceptions:

PendingState is a variable or contains a partial byte list or a byte list with an element which is a variable:

instantiation_error

PendingState is neither a variable nor a compound term:

type_error(compound,PendingState)

PendingState is not a valid authenticated channel pending-state term:

domain_error(authenticated_channel_pending_state,PendingState)

PendingState contains a key field which is not a list of 32 bytes:

type_error(list(byte,32),Bytes)

PendingState contains a signature field which is not a list of 64 bytes:

type_error(list(byte,64),Signature)

PendingState contains a non-integer byte:

type_error(integer,Byte)

PendingState contains an integer outside the byte range:

domain_error(byte,Byte)

Response is a variable or contains a partial byte list or a byte list with an element which is a variable:

instantiation_error

Response is neither a variable nor a compound term:

type_error(compound,Response)

Response is not a valid authenticated channel response term:

domain_error(authenticated_channel_response,Response)

Response contains a key field which is not a list of 32 bytes:

type_error(list(byte,32),Bytes)

Response contains a signature field which is not a list of 64 bytes:

type_error(list(byte,64),Signature)

Response contains a non-integer byte:

type_error(integer,Byte)

Response contains an integer outside the byte range:

domain_error(byte,Byte)

`authenticated_channel_encrypt/5`

Encrypts and authenticates Plaintext and returns Message and the replacement Channel state. The caller must discard the input state.

Compilation flags:

static

Template:

authenticated_channel_encrypt(Channel0,AAD,Plaintext,Message,Channel)

Mode and number of proofs:

authenticated_channel_encrypt(+compound,+list(byte),+list(byte),-compound,-compound) - one_or_error

Exceptions:

Channel0 is a variable or contains a partial byte list, a byte list with an element which is a variable, or a variable counter:

instantiation_error

Channel0 is neither a variable nor a compound term:

type_error(compound,Channel0)

Channel0 is not a valid authenticated channel state term:

domain_error(authenticated_channel_state,Channel0)

Channel0 contains a hash or key field which is not a list of 32 bytes:

type_error(list(byte,32),Bytes)

Channel0 contains a nonce-prefix field which is not a list of 16 bytes:

type_error(list(byte,16),Bytes)

Channel0 contains a non-integer byte:

type_error(integer,Byte)

Channel0 contains an integer outside the byte range:

domain_error(byte,Byte)

Channel0 contains a counter which is not an integer:

type_error(integer,Counter)

Channel0 contains a negative counter:

domain_error(non_negative_integer,Counter)

AAD is a partial list or a list with an element which is a variable:

instantiation_error

AAD is neither a variable nor a list of bytes:

type_error(list(byte),AAD)

AAD contains a non-integer byte:

type_error(integer,Byte)

AAD contains an integer outside the byte range:

domain_error(byte,Byte)

Plaintext is a partial list or a list with an element which is a variable:

instantiation_error

Plaintext is neither a variable nor a list of bytes:

type_error(list(byte),Plaintext)

Plaintext contains a non-integer byte:

type_error(integer,Byte)

Plaintext contains an integer outside the byte range:

domain_error(byte,Byte)

Channel0 send counter is exhausted:

resource_error(authenticated_channel_counter)

`authenticated_channel_decrypt/5`

Authenticates and decrypts the next strictly ordered Message and returns Plaintext and the replacement Channel state. The caller must discard the input state.

Compilation flags:

static

Template:

authenticated_channel_decrypt(Channel0,AAD,Message,Plaintext,Channel)

Mode and number of proofs:

authenticated_channel_decrypt(+compound,+list(byte),+compound,-list(byte),-compound) - zero_or_one_or_error

Exceptions:

Channel0 is a variable or contains a partial byte list, a byte list with an element which is a variable, or a variable counter:

instantiation_error

Channel0 is neither a variable nor a compound term:

type_error(compound,Channel0)

Channel0 is not a valid authenticated channel state term:

domain_error(authenticated_channel_state,Channel0)

Channel0 contains a hash or key field which is not a list of 32 bytes:

type_error(list(byte,32),Bytes)

Channel0 contains a nonce-prefix field which is not a list of 16 bytes:

type_error(list(byte,16),Bytes)

Channel0 contains a non-integer byte:

type_error(integer,Byte)

Channel0 contains an integer outside the byte range:

domain_error(byte,Byte)

Channel0 contains a counter which is not an integer:

type_error(integer,Counter)

Channel0 contains a negative counter:

domain_error(non_negative_integer,Counter)

AAD is a partial list or a list with an element which is a variable:

instantiation_error

AAD is neither a variable nor a list of bytes:

type_error(list(byte),AAD)

AAD contains a non-integer byte:

type_error(integer,Byte)

AAD contains an integer outside the byte range:

domain_error(byte,Byte)

Message is a variable or contains a partial byte list, a byte list with an element which is a variable, or a variable counter:

instantiation_error

Message is neither a variable nor a compound term:

type_error(compound,Message)

Message is not a valid authenticated channel message term:

domain_error(authenticated_channel_message,Message)

Message counter is not an integer:

type_error(integer,Counter)

Message counter is negative:

domain_error(non_negative_integer,Counter)

Message ciphertext and tag is not a list of bytes:

type_error(list(byte),CiphertextAndTag)

Message ciphertext and tag contains a non-integer byte:

type_error(integer,Byte)

Message ciphertext and tag contains an integer outside the byte range:

domain_error(byte,Byte)

Message ciphertext and tag is shorter than 16 bytes:

domain_error(minimum_byte_length(16),CiphertextAndTag)

Channel0 receive counter is exhausted:

resource_error(authenticated_channel_counter)

`authenticated_channel`

Public predicates 

`authenticated_channel_initiate/4`

`authenticated_channel_accept/5`

`authenticated_channel_finalize/3`

`authenticated_channel_encrypt/5`

`authenticated_channel_decrypt/5`

Protected predicates 

Private predicates 

Operators 

authenticated_channel

`authenticated_channel`