Tcl Requires Chilkat v11.0.0+

RSA SHA256 Signature using Private Key from Java Keystore

See more RSA Examples

Signs plaintext using RSA SHA256 using a key from a Java keystore.

Duplicatest this code:

KeyStore keystore; // key repository for keys containing signature certificate
String alias; // alias for the certificate in the key repository
String password; // password for the certificate's private key
String plaintext; // text being signed


Signature signature = Signature.getInstance("SHA256withRSA");
signature.initSign((PrivateKey) keystore.getKey(alias, password.toCharArray()));
signature.update(plaintext.getBytes("UTF-8"));
byte[] rsa_text= signature.sign();

Tcl

load ./chilkat.dll

set success 0

#  This requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

set jks [new_CkJavaKeyStore]

set jksPassword "secret"

#  Load the Java keystore from a file.  The JKS file password is used
#  to verify the keyed digest that is found at the very end of the keystore.
#  It verifies that the keystore has not been modified.
set success [CkJavaKeyStore_LoadFile $jks $jksPassword "qa_data/jks/sample_secret.jks"]
if {$success == 0} then {
    puts [CkJavaKeyStore_lastErrorText $jks]
    delete_CkJavaKeyStore $jks
    exit
}

#  Get the private key from the JKS.
#  The private key password may be different than the file password.
set privKeyPassword "secret"
set caseSensitive 0
set privKey [new_CkPrivateKey]

set success [CkJavaKeyStore_PrivateKeyOf $jks $privKeyPassword "some.alias" $caseSensitive $privKey]
if {$success == 0} then {
    puts [CkJavaKeyStore_lastErrorText $jks]
    delete_CkJavaKeyStore $jks
    delete_CkPrivateKey $privKey
    exit
}

#  Establish the RSA object and tell it to use the private key..
set rsa [new_CkRsa]

set success [CkRsa_UsePrivateKey $rsa $privKey]
if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkJavaKeyStore $jks
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    exit
}

#  Indicate we'll be signing the utf-8 byte representation of the string..
CkRsa_put_Charset $rsa "utf-8"

#  Sign some plaintext using RSA-SHA256
set binarySignature [new_CkByteData]

set plaintext "this is the text to be signed"
set success [CkRsa_SignString $rsa $plaintext "SHA256" $binarySignature]
if {[CkRsa_get_LastMethodSuccess $rsa] == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkJavaKeyStore $jks
    delete_CkPrivateKey $privKey
    delete_CkRsa $rsa
    delete_CkByteData $binarySignature
    exit
}

#  Alternatively, if the signature is desired in some encoded string form,
#  such as base64, base64-url, hex, etc.
CkRsa_put_EncodingMode $rsa "base64-url"
set signatureStr [CkRsa_signStringENC $rsa $plaintext "SHA256"]
puts "base64-url RSA signature: $signatureStr"

delete_CkJavaKeyStore $jks
delete_CkPrivateKey $privKey
delete_CkRsa $rsa
delete_CkByteData $binarySignature