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Encrypt a file to a PKCS7 encrypted message using multiple certificates from different users

See more Encryption Examples

Demonstrates how to encrypt a file to a PKCS7 encrypted message using multiple certificates from different users. Any one of the users can decrypt using his/her own certificate + private key.

Note: When doing public key encryption, it is the public key that is used to encrypt. The private key is required for decryption.

Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

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

    const crypt = try chilkat.Crypt2.init();
    defer crypt.deinit();

    // Tell the crypt object to use 3 certificates.
    // Do this by calling AddEncryptCert for each certificate.

    // 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).
    const cert1 = try chilkat.Cert.init();
    defer cert1.deinit();
    try cert1.loadFromFile("qa_data/user1/cert_user1.pem");
    // Assume success for the example, but make sure your application checks for success/failure...
    crypt.addEncryptCert(cert1);

    const cert2 = try chilkat.Cert.init();
    defer cert2.deinit();
    try cert2.loadFromFile("qa_data/user2/cert_user2.pem");
    crypt.addEncryptCert(cert2);

    const cert3 = try chilkat.Cert.init();
    defer cert3.deinit();
    try cert3.loadFromFile("qa_data/user3/cert_user3.pem");
    crypt.addEncryptCert(cert3);

    // 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.
    crypt.setCryptAlgorithm("pki");
    crypt.setPkcs7CryptAlg("aes");
    crypt.setKeyLength(128);
    crypt.setOaepHash("sha256");
    crypt.setOaepPadding(true);

    // Load the file to be encrypted...
    const file_data = try chilkat.BinData.init();
    defer file_data.deinit();
    try file_data.loadFile("qa_data/jpg/penguins.jpg");
    // Your app should check for success/failure..

    // Encrypt the data.  The contents of the fileData object are replaced with the PKCS7 encrypted message.
    crypt.encryptBd(file_data) catch {
        std.debug.print("{s}\n", .{try crypt.getLastErrorText(alloc)});
        return;
    };

    // Save the PKCS7 encrypted message to a file..
    try file_data.writeFile("qa_output/pkcs7_encrypted.p7");

    // Now indicate that the PKCS7 output is to be returned in the base64 encoding.
    crypt.setEncodingMode("base64");

    std.debug.print("OK.\n", .{});
}