anEnc

(c) 2020 Orange Number. Written by Gon Yi. https://gonyyi.com/copyright.txt

anEnc is an encryption library which includes:

• RSA
• AES-256 CBC (compatible with OpenSSL)
• SHA-256
• Encoding
  • Base 64
  • HEX

Note: Any function or method with the prefix Must will not return an error. Instead it will take a fallback value in addition to its necessary parameter(s). (eg: func MustHexDec(b, fallback []byte) []byte vs func HexDec(b []byte) ([]byte, error))

Note: Any function or method with a suffix i will take either io.Reader or io.Writer interface.
(eg: func SHA256i(ior io.Reader) ([]byte, error))

---

RSA

There are 4 key byte slice variables in an RSA struct.

• PEMPrivate
• PEMPublic
• DataEncrypted
• DataPlain

What needs to be filled?

• Encrypt:
  • PEMPublic + DataPlain = DataEncrypted
  • or PEMPrivate + DataPlain = DataEncrypted
    (this is because you can create a public key from the private key)
• Decrypt:
  • PEMPrivate + DataEncrypted = DataPlain

Usage: Encrypt

For encryption, the public key is needed. However, this can be generated from the corresponding private key. When rsa.Encrypt() runs, it will check if the public key is available, if not, it will generate a public key to encrypt.

rsa := anenc.NewRSA()

privKey := "-----BEGIN RSA PRIVATE KEY-----\nMIIEogIBAAKCAQEAsEWW0PcM2+...."

rsa.SetPEMPrivate(privKey) // set string of private key
// rsa.PEMPrivate = []byte(privKey) // OR byte slice of private key

rsa.SetDataPlain("this is my secret data")
// rsa.DataPlain = []byte(rawTxt) // OR byte slice can be used

if err := rsa.Encrypt(); err != nil {
    t.Errorf(err.Error())
    t.Fail()
}

Usage: Decrypt

When decrypting, the private key is needed along with the encrypted data.

rsa := anenc.NewRSA()
privKey := "-----BEGIN RSA PRIVATE KEY-----\nMIIEogIBAAKCAQEAsEWW0PcM2+...."

// SetPEMPrivate() and GetPEMPrivate() will deal with string type.
rsa.SetPEMPrivate(privKey)

// If encrypted data is byte slice, it can directly added by
// rsa.DataEncrypted = encryptedDataBytes
rsa.SetDataEncrypted("G85iGLFvqGdVWb00+pdVIo8cRPNzBABFBntHE1VXV1P96CipIHglnUL1v3rwy74...")

if err := rsa.Decrypt(); err != nil {
    println(err.Error())
} else {
    println(rsa.GetDataPlain())
}

---

AES

OpenSSL is compatible with the AES 256 CBC algorithm; it can be tested with OpenSSL as below.

Usage: Encrypt

aes := anenc.NewAES( []byte("myPwd") )
encrypted, _ := aes.Encrypt( []byte("mySecretDataGoeshere") )
println(base64.StdEncoding.EncodeToString(encrypted)) // ret: U2FsdGVkX1+vBuzVPzcCUSIVkzya0fH/Cbuw4YG8ZxDSu1mDiAC0FHWWZ/ncpB0W

> echo "U2FsdGVkX1+vBuzVPzcCUSIVkzya0fH/Cbuw4YG8ZxDSu1mDiAC0FHWWZ/ncpB0W" | openssl enc -d -aes-256-cbc -a -k myPwd
  mySecretDataGoeshere

Usage: Decrypt

echo "gon is always gone" | openssl enc -e -aes-256-cbc -a -k myPwd
  U2FsdGVkX19xNwC5ILkb94ffvVNhQTIUbGExFAHcyaQ3LkN4GR2CqT5Xu5LjI8bi

b64decoded, _ := base64.StdEncoding.DecodeString("U2FsdGVkX19xNwC5ILkb94ffvVNhQTIUbGExFAHcyaQ3LkN4GR2CqT5Xu5LjI8bi")
decoded, _ := aes.Decrypt( b64decoded )
println(string(decoded)) // ret: gon is always gone