Jenkins script console decrypt base64 encoded string

rsa_decrypt.groovy

//http://www.mysamplecode.com/2011/08/java-rsa-encrypt-string-using-bouncy.html
import jenkins.bouncycastle.api.PEMEncodable
import static jenkins.bouncycastle.api.PEMEncodable.decode
import hudson.util.Secret

import java.util.Base64

import org.bouncycastle.crypto.engines.RSAEngine
import org.bouncycastle.crypto.AsymmetricBlockCipher
import org.bouncycastle.crypto.params.AsymmetricKeyParameter
import org.bouncycastle.crypto.util.PrivateKeyFactory


String  encrypted_string = "Tye2N35iNoSe0ixZ0GnNHvjo4RvDLx2qq/NhFcq8tLVqOiVVX2HacdpijFdS1MkOQvk9sylNbcXNTW2yvXXFjyPLmTwxQPl9z7Eymfz37QsGy57TQURFikVIrOrrlw8f30Fizk23JnmI20fWgbv157o6CTWPC314jHE/Xy+kSF0="
String priv_key = '''
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
'''.trim()

Secret p = Secret.fromString('')
// https://howtodoinjava.com/java-8/base64-encoding-and-decoding-example-in-java-8/
AsymmetricBlockCipher e = new RSAEngine()
e = new org.bouncycastle.crypto.encodings.PKCS1Encoding(e)
key_pair = decode(priv_key, ((p)? p.plainText : null) as char[])
key = key_pair.toPrivateKey()
AsymmetricKeyParameter privateKey = (AsymmetricKeyParameter) PrivateKeyFactory.createKey(key.encoded)
e.init(false, privateKey)

byte[] messageBytes = Base64.decoder.decode(encrypted_string)
byte[] hexEncodedCipher = e.processBlock(messageBytes, 0, messageBytes.length)
outputData = new String(hexEncodedCipher)
println outputData

Helpful links

• https://stackoverflow.com/questions/3711754/why-java-security-nosuchproviderexception-no-such-provider-bc
• http://www.mysamplecode.com/2011/08/rsa-encryption-decryption-using-bouncy.html
  • http://www.mysamplecode.com/2011/08/java-rsa-encrypt-string-using-bouncy.html
  • http://www.mysamplecode.com/2011/08/java-rsa-decrypt-string-using-bouncy.html

This research was incorporated into my Jervis project. https://github.com/samrocketman/jervis/blob/jervis-1.0/src/main/groovy/net/gleske/jervis/tools/securityIO.groovy#L45-L60