(Tcl) RSAES-OAEP Encrypt String with AES-128 Content Encryption and SHA256

Encrypts a string using RSAES-OAEP with SHA256 and AES-128 content encryption to produce PKCS7 output (base64 encoded).

Note: This example requires Chilkat v9.5.0.67 or greater.

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

# First build a string to be encrypted
set sb [new_CkStringBuilder]

set i 1
while {$i < 25} {
    CkStringBuilder_AppendInt $sb $i
    CkStringBuilder_Append $sb " the quick brown fox jumped over the lazy dog.\r\n"
    set i [expr $i + 1]
}

puts [CkStringBuilder_getAsString $sb]

# The string to be encrypted looks like this:

# 1 the quick brown fox jumped over the lazy dog.
# 2 the quick brown fox jumped over the lazy dog.
# 3 the quick brown fox jumped over the lazy dog.
# 4 the quick brown fox jumped over the lazy dog.
# 5 the quick brown fox jumped over the lazy dog.
# 6 the quick brown fox jumped over the lazy dog.
# ...

# Load a digital certificate. 
# We don't need the private key for encryption.
# Only the public key is needed (which is included in a certificate).
set cert [new_CkCert]

set success [CkCert_LoadFromFile $cert "qa_data/rsaes-oaep/cert.pem"]
if {$success != 1} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkStringBuilder $sb
    delete_CkCert $cert
    exit
}

set crypt [new_CkCrypt2]

# Tell the crypt object to use the certificate.
CkCrypt2_SetEncryptCert $crypt $cert

# Indicate that we want PKI encryption (i.e. public-key infrastructure)
# to produce a CMS message (Cryptographic Message Syntax/PKCS7),
# that is be created with RSAES-OAEP padding, SHA256, and AES-128 for the
# bulk encryption.
CkCrypt2_put_CryptAlgorithm $crypt "pki"
CkCrypt2_put_Pkcs7CryptAlg $crypt "aes"
CkCrypt2_put_KeyLength $crypt 128
CkCrypt2_put_OaepHash $crypt "sha256"
CkCrypt2_put_OaepPadding $crypt 1

# Also, don't forget to be specific about the character encoding (byte representation) of the
# string to be encrypted.
CkCrypt2_put_Charset $crypt "utf-8"

# Now indicate that the PKCS7 output is to be returned in the base64 encoding.
CkCrypt2_put_EncodingMode $crypt "base64"

set base64Pkcs7 [CkCrypt2_encryptStringENC $crypt [CkStringBuilder_getAsString $sb]]
if {[CkCrypt2_get_LastMethodSuccess $crypt] != 1} then {
    puts [CkCrypt2_lastErrorText $crypt]
    delete_CkStringBuilder $sb
    delete_CkCert $cert
    delete_CkCrypt2 $crypt
    exit
}

# Show the output
puts "$base64Pkcs7"

# This base64 can be copy-and-pasted into the form at http://lapo.it/asn1js/
# to verify that all the chosen algorithms were indeed used.

puts "OK."

delete_CkStringBuilder $sb
delete_CkCert $cert
delete_CkCrypt2 $crypt