Cryptox

The cryptox package provides a unified interface for encryption/decryption and digital signing across multiple algorithms.

Interfaces

Cipher

For encryption and decryption:

type Cipher interface {
    Encrypt(plaintext string) (string, error)
    Decrypt(ciphertext string) (string, error)
}

Signer

For signing and verification:

type Signer interface {
    Sign(data string) (signature string, err error)
    Verify(data, signature string) (bool, error)
}

CipherSigner

Combined encryption and signing:

type CipherSigner interface {
    Cipher
    Signer
}

FixedIVDecrypter

FixedIVDecrypter is implemented by block-cipher modes that can decrypt external ciphertext produced with a caller-supplied constant IV:

type FixedIVDecrypter interface {
    DecryptWithFixedIV(ciphertext string) (string, error)
}

Native VEF ciphertext carries a fresh random IV and should use Cipher.Decrypt. DecryptWithFixedIV is an interop escape hatch for AES-CBC/SM4-CBC peers that send base64 ciphertext without the prepended IV; the fixed IV must have been configured with WithAESIv or WithSM4Iv.

Supported Algorithms

All constructors return the framework's Cipher / Signer / CipherSigner interface. Encoding helpers are algorithm-specific: AES and SM4 expose *FromHex / *FromBase64, RSA/SM2/ECDSA expose *FromPEM / *FromHex / *FromBase64, and ECIES exposes byte, hex, and base64 constructors.

AES (Symmetric Encryption)

import "github.com/coldsmirk/vef-framework-go/cryptox"

// key must be 16 / 24 / 32 bytes. Default mode is GCM (authenticated; IV is generated per call).
cipher, err := cryptox.NewAES(key)

// Use CBC instead. Encrypt generates a fresh IV and prepends it to ciphertext.
cbcCipher, err := cryptox.NewAES(key,
    cryptox.WithAESMode(cryptox.AesModeCbc),
)

encrypted, err := cipher.Encrypt("hello world")
plaintext, err := cipher.Decrypt(encrypted)

Variants: cryptox.NewAESFromHex(keyHex, ...), cryptox.NewAESFromBase64(keyBase64, ...).

For AES-CBC interop with peers that send bare ciphertext without a prepended IV, configure the fixed IV and call FixedIVDecrypter.DecryptWithFixedIV:

fixedCipher, err := cryptox.NewAES(key,
    cryptox.WithAESMode(cryptox.AesModeCbc),
    cryptox.WithAESIv(iv), // 16 bytes
)
plaintext, err := fixedCipher.(cryptox.FixedIVDecrypter).DecryptWithFixedIV(peerCiphertext)

RSA (Asymmetric Encryption + Signing)

// Private key comes first.
cipher, err := cryptox.NewRSAFromPEM(privatePEM, publicPEM)

encrypted, err := cipher.Encrypt("sensitive data")
plaintext, err := cipher.Decrypt(encrypted)

signature, err := cipher.Sign("important message")
valid, err := cipher.Verify("important message", signature)

Variants: cryptox.NewRSA(privateKey, publicKey) (from *rsa.PrivateKey / *rsa.PublicKey), cryptox.NewRSAFromHex, cryptox.NewRSAFromBase64.

Default RSA encryption mode is RsaModeOAEP; default signing mode is RsaSignModePSS. RsaModePKCS1v15 and RsaSignModePKCS1v15 are explicit legacy-interoperability choices.

SM2 (Chinese National Standard — Asymmetric)

// Private key comes first.
cipher, err := cryptox.NewSM2FromPEM(privatePEM, publicPEM)

encrypted, err := cipher.Encrypt("data")
plaintext, err := cipher.Decrypt(encrypted)

signature, err := cipher.Sign("data")
valid, err := cipher.Verify("data", signature)

Variants: cryptox.NewSM2(privateKey, publicKey), cryptox.NewSM2FromHex, cryptox.NewSM2FromBase64.

SM4 (Chinese National Standard — Symmetric)

// SM4 uses CBC. Encrypt generates a fresh IV and prepends it to ciphertext.
cipher, err := cryptox.NewSM4(key) // key: 16 bytes

encrypted, err := cipher.Encrypt("data")
plaintext, err := cipher.Decrypt(encrypted)

Variants: cryptox.NewSM4FromHex, cryptox.NewSM4FromBase64.

For SM4-CBC interop with peers that send bare ciphertext without a prepended IV, configure the fixed IV and call FixedIVDecrypter.DecryptWithFixedIV:

fixedCipher, err := cryptox.NewSM4(key, cryptox.WithSM4Iv(iv))
plaintext, err := fixedCipher.(cryptox.FixedIVDecrypter).DecryptWithFixedIV(peerCiphertext)

ECDSA (Signing Only)

// Private key comes first.
signer, err := cryptox.NewECDSAFromPEM(privatePEM, publicPEM)

signature, err := signer.Sign("data to sign")
valid, err := signer.Verify("data to sign", signature)

Variants: cryptox.NewECDSA(privateKey, publicKey), cryptox.NewECDSAFromHex, cryptox.NewECDSAFromBase64.

ECIES (Encryption Only)

ECIES additionally requires the curve identifier:

// Private key bytes first, then public key bytes, then the curve.
cipher, err := cryptox.NewECIESFromBytes(privateKeyBytes, publicKeyBytes, cryptox.EciesCurveP256)

encrypted, err := cipher.Encrypt("secret data")
plaintext, err := cipher.Decrypt(encrypted)

Variants: cryptox.NewECIES(privateKey, publicKey) (from *ecdh.PrivateKey / *ecdh.PublicKey), cryptox.NewECIESFromHex(..., curve), cryptox.NewECIESFromBase64(..., curve). Supported curves: EciesCurveP256, EciesCurveP384, EciesCurveP521, EciesCurveX25519.

GenerateECIESKey(curve) and ECIES byte parsers use the requested ECIESCurve; an unknown curve value falls back to P-256. GenerateECDSAKey does the same for ECDSACurve.

Algorithm Comparison

Algorithm	Type	Encrypt	Sign	Standard
AES	Symmetric	✅	❌	International
RSA	Asymmetric	✅	✅	International
ECDSA	Asymmetric	❌	✅	International
ECIES	Asymmetric	✅	❌	International
SM2	Asymmetric	✅	✅	Chinese (国密)
SM4	Symmetric	✅	❌	Chinese (国密)

Options, Constants, and Key Helpers

Area	Public API
AES modes/options	AESMode, AesModeGcm, AesModeCbc, WithAESMode(mode), WithAESIv(iv)
RSA modes/options	RSAMode, RSASignMode, RsaModeOAEP, RsaModePKCS1v15, RsaSignModePSS, RsaSignModePKCS1v15, WithRSAMode(mode), WithRSASignMode(mode)
SM4 options	WithSM4Iv(iv)
ECDSA curves	ECDSACurve, EcdsaCurveP224, EcdsaCurveP256, EcdsaCurveP384, EcdsaCurveP521
ECIES curves	ECIESCurve, EciesCurveP256, EciesCurveP384, EciesCurveP521, EciesCurveX25519
key helpers	GenerateECDSAKey(curve), GenerateECIESKey(curve)
option types	AESOption, RSAOption, SM4Option

Error Sentinels

Group	Errors
key availability	ErrAtLeastOneKeyRequired, ErrPublicKeyRequiredForEncrypt, ErrPrivateKeyRequiredForDecrypt, ErrPrivateKeyRequiredForSign, ErrPublicKeyRequiredForVerify
key parsing/type	ErrFailedDecodePEMBlock, ErrUnsupportedPEMType, ErrNotRSAPrivateKey, ErrNotRSAPublicKey, ErrNotECDSAPrivateKey, ErrNotECDSAPublicKey
symmetric crypto	ErrInvalidAESKeySize, ErrInvalidSM4KeySize, ErrInvalidIVSizeCBC, ErrCiphertextNotMultipleOfBlock, ErrCiphertextTooShort, ErrInvalidPadding
input/signature	ErrDataEmpty, ErrInvalidSignature