crypto

Documentation

Overview

Package crypto defines the cryptographic functions used in E4

Index

• Constants
• Variables
• func Decrypt(key, ad, ct []byte) ([]byte, error)
• func DeriveSymKey(pwd string) ([]byte, error)
• func Encrypt(key, ad, pt []byte) ([]byte, error)
• func HashIDAlias(idalias string) []byte
• func HashTopic(topic string) []byte
• func ProtectSymKey(payload, key []byte) ([]byte, error)
• func RandomDelta16() uint16
• func RandomID() []byte
• func RandomKey() []byte
• func Sha3Sum256(data []byte) []byte
• func Sign(signerID []byte, privateKey Ed25519PrivateKey, timestamp []byte, ...) ([]byte, error)
• func UnprotectSymKey(protected, key []byte) ([]byte, error)
• func ValidateCurve25519PrivKey(key []byte) error
• func ValidateCurve25519PubKey(key []byte) error
• func ValidateEd25519PrivKey(key []byte) error
• func ValidateEd25519PubKey(key []byte) error
• func ValidateID(id []byte) error
• func ValidateName(name string) error
• func ValidatePassword(password string) error
• func ValidateSymKey(key []byte) error
• func ValidateTimestamp(timestamp []byte) error
• func ValidateTimestampKey(timestamp []byte) error
• func ValidateTopic(topic string) error
• func ValidateTopicHash(topicHash []byte) error
• type Curve25519PrivateKey
  • func PrivateEd25519KeyToCurve25519(edPrivKey Ed25519PrivateKey) Curve25519PrivateKey
• type Curve25519PublicKey
  • func PublicEd25519KeyToCurve25519(edPubKey Ed25519PublicKey) Curve25519PublicKey
• type Ed25519PrivateKey
  • func Ed25519PrivateKeyFromPassword(password string) (Ed25519PrivateKey, error)
• type Ed25519PublicKey

Constants

const (
	// IDLen is the length of an E4 ID
	IDLen = 16
	// KeyLen is the length of a symmetric key
	KeyLen = 32
	// TagLen is the length of the authentication tag appended to the cipher
	TagLen = 16
	// HashLen is the length of a hashed topic
	HashLen = 16
	// TimestampLen is the length of the timestamp
	TimestampLen = 8
	// MaxTopicLen is the maximum length of a topic
	MaxTopicLen = 512
	// MaxDelayDuration is the validity time of a protected message
	MaxDelayDuration = 10 * time.Minute
	// MaxDelayKeyTransition is the validity time of an old topic key once updated
	MaxDelayKeyTransition = 60 * time.Minute
	// IDLenHex is the length of a hexadecimal encoded ID
	IDLenHex = IDLen * 2
	// KeyLenHex is the length of a hexadecimal encoded key
	KeyLenHex = KeyLen * 2

	// Curve25519PubKeyLen is the length of a curve25519 public key
	Curve25519PubKeyLen = 32
	// Curve25519PrivKeyLen is the length of a curve25519 private key
	Curve25519PrivKeyLen = 32
)

List of global e4 constants

const (
	// PasswordMinLength defines the minimum size accepted for a password
	PasswordMinLength = 16
	// NameMinLen is the minimum length of a name
	NameMinLen = 1
	// NameMaxLen is the maximum length of a name
	NameMaxLen = 255
)

Variables

var (
	// ErrInvalidProtectedLen occurs when the protected message is  not of the expected length
	ErrInvalidProtectedLen = errors.New("invalid length of protected message")
	// ErrTooShortCiphertext occurs when trying to unprotect a ciphertext shorter than TimestampLen
	ErrTooShortCiphertext = errors.New("ciphertext too short")
	// ErrTimestampInFuture occurs when the cipher timestamp is in the future
	ErrTimestampInFuture = errors.New("timestamp received is in the future")
	// ErrTimestampTooOld occurs when the cipher timestamp is older than MaxDelayDuration from now
	ErrTimestampTooOld = errors.New("timestamp too old")
	// ErrInvalidSignature occurs when a signature verification fails
	ErrInvalidSignature = errors.New("invalid signature")
	// ErrInvalidSignerID occurs when trying to sign with an invalid ID
	ErrInvalidSignerID = errors.New("invalid signer ID")
	// ErrInvalidTimestamp occurs when trying to sign with an invalid timestamp
	ErrInvalidTimestamp = errors.New("invalid timestamp")
)

Functions

func Decrypt

func Decrypt(key, ad, ct []byte) ([]byte, error)

Decrypt decrypts and verifies an authenticated ciphertext

func DeriveSymKey

func DeriveSymKey(pwd string) ([]byte, error)

DeriveSymKey derives a symmetric key from a password using Argon2 (Replaces HashPwd)

func Encrypt

func Encrypt(key, ad, pt []byte) ([]byte, error)

Encrypt creates an authenticated ciphertext

func HashIDAlias

func HashIDAlias(idalias string) []byte

HashIDAlias creates an ID from an ID alias string

func HashTopic

func HashTopic(topic string) []byte

HashTopic creates a topic hash from a topic string

func ProtectSymKey

func ProtectSymKey(payload, key []byte) ([]byte, error)

ProtectSymKey attempt to encrypt payload using given symmetric key

func RandomDelta16

func RandomDelta16() uint16

RandomDelta16 produces a random 16-bit integer to allow us to vary key sizes, plaintext sizes etc

func RandomID

func RandomID() []byte

RandomID generates a random IDLen-byte ID

func RandomKey

func RandomKey() []byte

RandomKey generates a random KeyLen-byte key usable by Encrypt and Decrypt

func Sha3Sum256

func Sha3Sum256(data []byte) []byte

Sha3Sum256 returns the sha3 sum of given data

func Sign

func Sign(signerID []byte, privateKey Ed25519PrivateKey, timestamp []byte, payload []byte) ([]byte, error)

Sign will sign the given payload using the given privateKey, producing an output composed of: timestamp + signedID + payload + signature

func UnprotectSymKey

func UnprotectSymKey(protected, key []byte) ([]byte, error)

UnprotectSymKey attempt to decrypt protected bytes, using given symmetric key

func ValidateCurve25519PrivKey

func ValidateCurve25519PrivKey(key []byte) error

ValidateCurve25519PrivKey checks that a key is of the expected length and not all zero

func ValidateCurve25519PubKey

func ValidateCurve25519PubKey(key []byte) error

ValidateCurve25519PubKey checks that a key is of the expected length and not all zero

func ValidateEd25519PrivKey

func ValidateEd25519PrivKey(key []byte) error

ValidateEd25519PrivKey checks that a key is of the expected length and not all zero

func ValidateEd25519PubKey

func ValidateEd25519PubKey(key []byte) error

ValidateEd25519PubKey checks that a key is of the expected length and not all zero

func ValidateID

func ValidateID(id []byte) error

ValidateID checks that an id is of the expected length

func ValidateName

func ValidateName(name string) error

ValidateName is used to validate names match given constraints since we hash these in the protocol, those constraints are quite liberal, but for correctness we check any string is valid UTF-8

func ValidatePassword

func ValidatePassword(password string) error

ValidatePassword checks given password is an utf8 string of at least PasswordMinLength characters

func ValidateSymKey

func ValidateSymKey(key []byte) error

ValidateSymKey checks that a key is of the expected length and not filled with zero

func ValidateTimestamp

func ValidateTimestamp(timestamp []byte) error

ValidateTimestamp checks that given timestamp bytes are a valid LittleEndian encoded timestamp, not in the future and not older than MaxDelayDuration

func ValidateTimestampKey

func ValidateTimestampKey(timestamp []byte) error

ValidateTimestampKey checks that given timestamp bytes are a valid LittleEndian encoded timestamp, not in the future and not older than MaxDelayKeyTransition

func ValidateTopic

func ValidateTopic(topic string) error

ValidateTopic checks if a topic is not too large or empty

func ValidateTopicHash

func ValidateTopicHash(topicHash []byte) error

ValidateTopicHash checks that a topic hash is of the expected length

Types

type Curve25519PrivateKey

type Curve25519PrivateKey = []byte

Curve25519PrivateKey defines an alias for curve 25519 private keys

func PrivateEd25519KeyToCurve25519

func PrivateEd25519KeyToCurve25519(edPrivKey Ed25519PrivateKey) Curve25519PrivateKey

PrivateEd25519KeyToCurve25519 convert an Ed25519PrivateKey to a Curve25519PrivateKey.

type Curve25519PublicKey

type Curve25519PublicKey = []byte

Curve25519PublicKey defines an alias for curve 25519 public keys

func PublicEd25519KeyToCurve25519

func PublicEd25519KeyToCurve25519(edPubKey Ed25519PublicKey) Curve25519PublicKey

PublicEd25519KeyToCurve25519 convert an Ed25519PublicKey to a Curve25519PublicKey.

type Ed25519PrivateKey

type Ed25519PrivateKey = []byte

Ed25519PrivateKey defines an alias for Ed25519 private keys

func Ed25519PrivateKeyFromPassword

func Ed25519PrivateKeyFromPassword(password string) (Ed25519PrivateKey, error)

Ed25519PrivateKeyFromPassword creates a ed25519.PrivateKey from a password

type Ed25519PublicKey

type Ed25519PublicKey = []byte

Ed25519PublicKey defines an alias for Ed25519 public keys