(Tcl) RSA SHA256 Signature using Private Key from Java Keystore

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();

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load ./chilkat.dll

# 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 != 1} 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
# privKey is a CkPrivateKey
set privKey [CkJavaKeyStore_FindPrivateKey $jks $privKeyPassword "some.alias" $caseSensitive]
if {[CkJavaKeyStore_get_LastMethodSuccess $jks] != 1} then {
    puts [CkJavaKeyStore_lastErrorText $jks]
    delete_CkJavaKeyStore $jks
    exit
}

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

set success [CkRsa_ImportPrivateKeyObj $rsa $privKey]
delete_CkPrivateKey $privKey

if {$success != 1} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkJavaKeyStore $jks
    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] != 1} then {
    puts [CkRsa_lastErrorText $rsa]
    delete_CkJavaKeyStore $jks
    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_CkRsa $rsa
delete_CkByteData $binarySignature