README.md

Crypto Utilities

The cryptoutils package provides a set of cryptographic utility functions for various encryption, decryption, and cryptographic operations. Below are the main features and methods of the package:

EncryptAES

• EncryptAES(plaintext, key []byte) (ciphertext []byte, nonce []byte, err error):
  Encrypts the given plaintext using AES-GCM with the provided key.
  • plaintext: The data to encrypt.
  • key: The AES encryption key.
  • Returns the encrypted ciphertext and the nonce used for encryption.

DecryptAES

• DecryptAES(ciphertext, key, nonce []byte) ([]byte, error):
  Decrypts the given ciphertext using AES-GCM (Galois/Counter Mode).
  • ciphertext: The encrypted data.
  • key: The AES decryption key.
  • nonce: The nonce used for encryption.
  • Returns the decrypted plaintext.

GenerateRSAKeyPair

• GenerateRSAKeyPair(bits int) (*rsa.PrivateKey, *rsa.PublicKey, error):
  Generates an RSA key pair with the specified number of bits.
  • bits: The size of the key in bits (e.g., 2048, 4096).
  • Returns the generated private and public keys.

EncryptRSA

• EncryptRSA(message []byte, pubKey *rsa.PublicKey) ([]byte, error):
  Encrypts a given message using RSA and the provided public key, using the OAEP padding scheme.
  • message: The data to encrypt.
  • pubKey: The RSA public key used for encryption.
  • Returns the encrypted ciphertext.

DecryptRSA

• DecryptRSA(ciphertext []byte, privKey *rsa.PrivateKey) ([]byte, error):
  Decrypts the given ciphertext using the provided RSA private key, using the OAEP padding scheme.
  • ciphertext: The encrypted data.
  • privKey: The RSA private key used for decryption.
  • Returns the decrypted plaintext.

GenerateECDSAKeyPair

• GenerateECDSAKeyPair(curve elliptic.Curve) (*ecdsa.PrivateKey, *ecdsa.PublicKey, error):
  Generates an ECDSA key pair using the specified elliptic curve.
  • curve: The elliptic curve to use for key generation (e.g., elliptic.P256()).
  • Returns the generated private and public keys.

ECDSASignASN1

• ECDSASignASN1(message []byte, privKey *ecdsa.PrivateKey) ([]byte, error):
  Generates an ECDSA signature in ASN.1 format for the given message using the provided private key.
  • message: The data to sign.
  • privKey: The ECDSA private key used for signing.
  • Returns the ASN.1 encoded signature.

ECDSAVerifyASN1

• ECDSAVerifyASN1(message, sig []byte, pubKey *ecdsa.PublicKey) bool:
  Verifies an ECDSA signature in ASN.1 format for a given message and public key.
  • message: The signed data.
  • sig: The signature to verify.
  • pubKey: The ECDSA public key used for verification.
  • Returns true if the signature is valid, false otherwise.

HashSHA256

• HashSHA256(input string) string:
  Computes the SHA-256 hash of the given input string and returns the resulting hash as a hexadecimal-encoded string.
  • input: The string to hash.
  • Returns the SHA-256 hash as a hexadecimal string.

GenerateHMAC

• GenerateHMAC(key, message []byte, hash hash.Hash) string:
  Generates a Hash-based Message Authentication Code (HMAC) using the provided key, message, and hash function (e.g., SHA-256).
  • key: The key used for HMAC generation.
  • message: The data to authenticate.
  • hash: The hash function to use for HMAC (e.g., sha256.New()).
  • Returns the HMAC as a hexadecimal string.

VerifyHMAC

• VerifyHMAC(key, message []byte, hash hash.Hash, HMAC string) bool:
  Verifies the integrity and authenticity of a message using HMAC.
  • key: The key used for HMAC generation.
  • message: The data to authenticate.
  • hash: The hash function used for HMAC generation.
  • HMAC: The expected HMAC value to verify.
  • Returns true if the HMAC is valid, false otherwise.

GenerateSecureToken

• GenerateSecureToken(length int) (string, error):
  Generates a cryptographically secure random token of the specified length.
  • length: The length of the generated token.
  • Returns the generated token as a hexadecimal string.

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Examples:

For examples of each function, please check out EXAMPLES.md

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