grokify/mogo

package rsautil

import (
    "crypto/md5" // #nosec G501
    "crypto/rand"
    "crypto/rsa"
    "encoding/base64"
    "errors"
    "hash"
    "os"
)

type CryptorOAEP struct {
    Hash          hash.Hash
    RsaPrivateKey *rsa.PrivateKey
    RsaPublicKey  *rsa.PublicKey
}

func NewCryptorOAEP() CryptorOAEP {
    return CryptorOAEP{Hash: md5.New()} // #nosec G401
}

func (enc *CryptorOAEP) DecryptOAEP(ciphertextBytes []byte, label []byte) ([]byte, error) {
    if enc.RsaPrivateKey == nil {
        return []byte{}, errors.New("401: RSA Private Key Not Set")
    }
    return rsa.DecryptOAEP(enc.Hash, rand.Reader, enc.RsaPrivateKey, ciphertextBytes, label)
}

func (enc *CryptorOAEP) DecryptOAEPBase64String(ciphertextBase64 string, label []byte) ([]byte, error) {
    ciphertextBytes, err := base64.StdEncoding.DecodeString(ciphertextBase64)
    if err != nil {
        return []byte(""), err
    }
    return enc.DecryptOAEP(ciphertextBytes, label)
}

func (enc *CryptorOAEP) DecryptOAEPBase64StringFromPath(ciphertextBase64Path string, label []byte) ([]byte, error) {
    ciphertextBase64Bytes, err := os.ReadFile(ciphertextBase64Path)
    if err != nil {
        return []byte(""), err
    }
    return enc.DecryptOAEPBase64String(string(ciphertextBase64Bytes), label)
}

func (enc *CryptorOAEP) EncryptOAEP(plaintextBytes []byte, label []byte) ([]byte, error) {
    if enc.RsaPublicKey == nil {
        err := errors.New("402: RSA Public Key Not Set")
        return []byte{}, err
    }
    return rsa.EncryptOAEP(enc.Hash, rand.Reader, enc.RsaPublicKey, plaintextBytes, label)
}

func (enc *CryptorOAEP) EncryptOAEPToBase64String(plaintextBytes []byte, label []byte) (string, error) {
    ciphertextBytes, err := enc.EncryptOAEP(plaintextBytes, label)
    if err != nil {
        return "", err
    }
    b64 := base64.StdEncoding.EncodeToString(ciphertextBytes)
    return b64, nil
}