(Tcl) Verify an RSA Signature Against the Signed Hash

See more Apple Keychain Examples

Demonstrates how to validate an RSA Signature against the hash that was signed.

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load ./chilkat.dll

set bd [new_CkBinData]

for {set i 0} {$i <= 100} {incr i} {
    CkBinData_AppendEncoded $bd "000102030405060708090A0B0C0D0E0F" "hex"
}
set sha256_base64 [CkBinData_getHash $bd "sha256" "base64"]
puts "sha256 hash in base64 format: $sha256_base64"

set base64_rsa_sig "AwF2BbOvL6jA5DwmMAc9n6J2Cc8PI6Rj5W079+aKJcIEtPWRzHor0Bvc3aftGM3Jbgj6SXlIC3M3RYS7UZOnfiHKFNZgbxaNT5WwsWooK42ZkC8DBZl0p7OunBUKd5SciUo+TKilioeUkriN3L1Zl9hwi3HVDVqgVo3XXskwIftSqLSFlepTLTmOWj9Y93dp8J4D9RyLtNgFQBc0WB22tyJTsuY56mLcWe1AMF3LizB9OrbwjynF2u16xWlrJdugccz795fJBUV9aQSD+8S3KeqwQhoi8RK1uhD68aGCyaSpBq0NZ8COAkn7MXaF4POxrAAt8udfHM+PRfSOptcH/w=="

# Get the public key to be used for signature verification.
set pubKey [new_CkPublicKey]

set success [CkPublicKey_LoadFromFile $pubKey "rsaKeys/chilkat-rsa-2048.pem"]
if {$success == 0} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkBinData $bd
    delete_CkPublicKey $pubKey
    exit
}

set rsa [new_CkRsa]

CkRsa_ImportPublicKeyObj $rsa $pubKey

# Verify the hash against the signature.
CkRsa_put_EncodingMode $rsa "base64"
set success [CkRsa_VerifyHashENC $rsa $sha256_base64 "sha256" $base64_rsa_sig]

if {$success == 0} then {
    puts [CkRsa_lastErrorText $rsa]
    puts "Signature invalid."
} else {
    puts "Signature valid."
}


delete_CkBinData $bd
delete_CkPublicKey $pubKey
delete_CkRsa $rsa