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‎Makefile

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APPS=openssl_tstpkcs12 mbedtls_tstpkcs12 openssl_rc2_crack openssl_sha1_perftest openssl_pkcs12_perftest openssl_des3_perftest openssl_pass_crack PdfEncryptionTest.class
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all: $(APPS)
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CXX=clang++
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sslflags=-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib -lcrypto -lssl
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mbedflags=-I /usr/local/include/ -L/usr/local/lib -lmbedcrypto
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cflags=-g -std=c++1z -Wall -O3
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mbedtls_tstpkcs12: mbedtls_tstpkcs12.cpp
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$(CXX) $^ -o $@ $(mbedflags) $(cflags)
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openssl_tstpkcs12: openssl_tstpkcs12.cpp
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$(CXX) $^ -o $@ $(sslflags) $(cflags)
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openssl_rc2_crack: openssl_rc2_crack.cpp
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$(CXX) $^ -o $@ $(sslflags) $(cflags)
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openssl_sha1_perftest: openssl_sha1_perftest.cpp
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$(CXX) $^ -o $@ $(sslflags) $(cflags)
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openssl_pkcs12_perftest: openssl_pkcs12_perftest.cpp
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$(CXX) $^ -o $@ $(sslflags) $(cflags)
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openssl_des3_perftest: openssl_des3_perftest.cpp
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$(CXX) $^ -o $@ $(sslflags) $(cflags)
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openssl_pass_crack: openssl_pass_crack.cpp
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$(CXX) $^ -o $@ $(sslflags) $(cflags)
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clean:
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$(RM) $(APPS)
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$(RM) -r $(wildcard *.dSYM)
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BC=$(HOME)/.m2/repository/org/bouncycastle/bcprov-jdk15on/1.49/bcprov-jdk15on-1.49.jar:$(HOME)/.m2/repository/org/bouncycastle/bcpkix-jdk15on/1.49/bcpkix-jdk15on-1.49.jar
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ITEXT=$(HOME)/gitprj/itext7
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PdfEncryptionTest.class: PdfEncryptionTest.java
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javac -classpath "$(ITEXT)/target/*:$(BC)" PdfEncryptionTest.java
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runjava:
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java -classpath ".:$(ITEXT)/target/*:$(BC)" PdfEncryptionTest
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‎PdfEncryptionTest.java

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/*
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* use itext to decrypt the pdf
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*/
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import com.itextpdf.io.font.FontConstants;
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import com.itextpdf.kernel.crypto.CryptoUtil;
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import com.itextpdf.kernel.PdfException;
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import com.itextpdf.kernel.crypto.BadPasswordException;
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import com.itextpdf.kernel.font.PdfFontFactory;
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import com.itextpdf.kernel.utils.CompareTool;
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import com.itextpdf.kernel.xmp.XMPException;
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import com.itextpdf.test.ExtendedITextTest;
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import com.itextpdf.test.ITextTest;
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import com.itextpdf.test.annotations.type.IntegrationTest;
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import org.bouncycastle.jce.provider.BouncyCastleProvider;
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import com.itextpdf.kernel.pdf.PdfReader;
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import com.itextpdf.kernel.pdf.PdfDocument;
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import com.itextpdf.kernel.pdf.PdfPage;
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import com.itextpdf.kernel.pdf.ReaderProperties;
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import java.io.FileInputStream;
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import java.io.IOException;
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import java.nio.charset.StandardCharsets;
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import java.security.GeneralSecurityException;
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import java.security.PrivateKey;
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import java.security.Security;
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import java.security.cert.Certificate;
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import java.security.cert.CertificateException;
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public class PdfEncryptionTest {
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public static Certificate getPublicCertificate(String path) throws IOException, CertificateException {
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FileInputStream is = new FileInputStream(path);
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return CryptoUtil.readPublicCertificate(is);
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}
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public static PrivateKey getPrivateKey(String filename, String password) throws GeneralSecurityException, IOException {
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return CryptoUtil.readPrivateKeyFromPKCS12KeyStore(new FileInputStream(filename), "sandbox", password.toCharArray());
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}
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public static void main(String [] args) throws IOException, CertificateException, GeneralSecurityException
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{
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Security.addProvider(new BouncyCastleProvider());
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String filename = args[0];
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Certificate certificate = getPublicCertificate(args[1]);
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PrivateKey privkey = getPrivateKey(args[1], args[2]);
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PdfReader reader = new PdfReader(filename, new ReaderProperties().setPublicKeySecurityParams(certificate, privkey, "BC", null));
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PdfDocument document = new PdfDocument(reader);
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PdfPage page = document.getPage(1);
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System.out.println("content = " + new String(page.getStreamBytes(0)));
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System.out.println("author = " + document.getDocumentInfo().getAuthor());
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System.out.println("creator = " + document.getDocumentInfo().getCreator());
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document.close();
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}
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}
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‎README.md

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Pdf Encryption
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==============
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Using sample data from:
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* https://github.com/itext/itext7/tree/develop/kernel/src/test/resources/com/itextpdf/kernel/pdf/PdfEncryptionTest
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Example code demonstating how pdf encryption with certificates works.
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python3 decryptpdf.py encryptedWithCertificateAes128.pdf test.p12 kspass
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Will output the following decrypted data:
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priv b'a2d0faa52fee8453fe20150505050505'
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cert b'37373532393731340808080808080808'
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seed = b'cd532522a3f5943f66479ab8b0aa32d0609a0e18'
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mkey= b'b1ce00167f01fc074d49d6fe18069b942ed9c428'
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b'Author' b'Alexander Chingarev\r\r\r\r\r\r\r\r\r\r\r\r\r'
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b'CreationDate' b"D:20160809103103-03'00'\t\t\t\t\t\t\t\t\t"
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b'Creator' b'iText 6\t\t\t\t\t\t\t\t\t'
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b'ModDate' b"D:20160809103103-03'00'\t\t\t\t\t\t\t\t\t"
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b'Producer' b'iText\xae 7.0.1-SNAPSHOT \xa92000-2016 iText Group NV (AGPL-version)\x02\x02'
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The repeating sequences at the end of each decrypted text are the PKCS1.5 padding.
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Pdf Parser
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==========
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As a side project i created a simple PDF parser, which outputs the parsing stack plus a list of objects.
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python pdfparser.py encryptedWithCertificateAes128.pdf
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producing the following output:
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[PdfComment: ascii:'PDF-1.7', PdfComment: hex:'e2e3cfd3',
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PdfOperator: xref,
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PdfNumber: 0, PdfNumber: 9,
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PdfNumber: 0000000000, PdfNumber: 65535, PdfOperator: f,
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PdfNumber: 0000000294, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000000873, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000000354, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000000161, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000000015, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000000785, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000000924, PdfNumber: 00000, PdfOperator: n,
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PdfNumber: 0000003847, PdfNumber: 00000, PdfOperator: n,
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PdfOperator: trailer, PdfDictionary: [
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PdfName: Encrypt, PdfReference: 00008.0,
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PdfName: ID, PdfArray: [PdfHexdata: eadf305edab34545d11859b727274d71, PdfHexdata: eadf305edab34545d11859b727274d71],
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PdfName: Info, PdfReference: 00003.0,
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PdfName: Root, PdfReference: 00001.0,
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PdfName: Size, PdfNumber: 9],
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PdfComment: ascii:'iText-7.0.1-SNAPSHOT',
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PdfOperator: startxref, PdfNumber: 4893]
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00001: PdfObject: [PdfDictionary: [
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PdfName: Metadata, PdfReference: 00007.0,
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PdfName: Pages, PdfReference: 00002.0,
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PdfName: Type,
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PdfName: Catalog]]
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00002: PdfObject: [PdfDictionary: [
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PdfName: Count, PdfNumber: 1,
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PdfName: Kids, PdfArray: [PdfReference: 00004.0],
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PdfName: Type,
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PdfName: Pages]]
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00003: PdfObject: [PdfDictionary: [
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PdfName: Author, PdfString: hex:'5b97d367c7310b9d80761c86e66fa2c71dab01fb150e6fa4c55cb4bf80fac19cda79513966f9d6c1e938080fc8c87800',
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PdfName: CreationDate, PdfString: hex:'5b97d367c7310b9d80761c86e66fa2c710cf138a9608a559cf8aa4e14fe9f97ee6e7ef89029fb1f7399dd9e64b0d7cab',
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PdfName: Creator, PdfString: hex:'5b97d367c7310b9d80761c86e66fa2c7ee23708d7b3f6973b01ff75dae7e0fca',
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PdfName: ModDate, PdfString: hex:'5b97d367c7310b9d80761c86e66fa2c710cf138a9608a559cf8aa4e14fe9f97ee6e7ef89029fb1f7399dd9e64b0d7cab',
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PdfName: Producer, PdfString: hex:'5b97d367c7310b9d80761c86e66fa2c7ba3a4b524f422411b737667f5c50c98f8e864b96999ed6247270483364dd492a28c0a6f50da37bfe8e0ad618f419d4e77f31179bf7502fd8606af1b81e271ae3']]
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00004: PdfObject: [PdfDictionary: [
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PdfName: Contents, PdfReference: 00005.0,
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PdfName: MediaBox, PdfArray: [PdfNumber: 0, PdfNumber: 0, PdfNumber: 595, PdfNumber: 842],
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PdfName: Parent, PdfReference: 00002.0,
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PdfName: Resources, PdfDictionary: [
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PdfName: Font, PdfDictionary: [
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PdfName: F1, PdfReference: 00006.0]],
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PdfName: TrimBox, PdfArray: [PdfNumber: 0, PdfNumber: 0, PdfNumber: 595, PdfNumber: 842],
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PdfName: Type,
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PdfName: Page]]
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00005: PdfObject: [PdfStream: PdfDictionary: [
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PdfName: Filter,
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PdfName: FlateDecode,
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PdfName: Length, PdfNumber: 80]]
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00006: PdfObject: [PdfDictionary: [
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PdfName: BaseFont,
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PdfName: Helvetica,
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PdfName: Encoding,
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PdfName: WinAnsiEncoding,
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PdfName: Subtype,
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PdfName: Type1,
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PdfName: Type,
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PdfName: Font]]
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00007: PdfObject: [PdfStream: PdfDictionary: [
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PdfName: Length, PdfNumber: 2848,
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PdfName: Subtype,
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PdfName: XML,
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PdfName: Type,
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PdfName: Metadata]]
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00008: PdfObject: [PdfDictionary: [
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PdfName: CF, PdfDictionary: [
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PdfName: DefaultCryptFilter, PdfDictionary: [
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PdfName: CFM,
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PdfName: AESV2,
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PdfName: Recipients, PdfArray: [PdfString: hex:'308201f706092a'...]]],
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PdfName: Filter,
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PdfName: Adobe.PubSec,
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PdfName: Length, PdfNumber: 128,
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PdfName: R, PdfNumber: 4,
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PdfName: StmF,
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PdfName: DefaultCryptFilter,
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PdfName: StrF,
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PdfName: DefaultCryptFilter,
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PdfName: SubFilter,
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PdfName: adbe.pkcs7.s5,
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PdfName: V, PdfNumber: 4]]
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Cracking a PKCS12 certificate
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=============================
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hexdump of the first couple of encrypted and decrypted blocks of the 40-bit RC2 encrypted certificate in test.p12:
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2408c5d658c61cad 43036642daa47c52 9023df09863bd662 28c700fee6c81f86 ac5d3c4debda9148 0ac6535dd9574d06 << cipher text
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3082____3082____ 060b2a864886f70d 010c0a0103a082__ __3082____060a2a 864886f70d010916 01a082____0482__ << plain text
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The length dependent parts have been replaced with '\_\_\_\_'.
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As you can see the 2nd block contains part of the 'pkcs12' OID representation,
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and will be the same for all PKCS12 encoded data.
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So we can use this as the known plain + cipher pair target for the brute force encryption.
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Since the cipher is used in CBC mode, we have to XOR the plaintext with the 1st cipher block
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2408c5d658c61cad XOR 060b2a864886f70d = 2203ef501040eba0
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And then do a full 40-bit search for the key:
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openssl_rc2_crack -e 43036642daa47c52 -p 2203ef501040eba0 -v
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Running on a single core, this will take about 5 days.
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Using the `-f` and `-t` parameters you can run several instances searching different parts
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of the keyspace.
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./openssl_rc2_crack -e 43036642daa47c52 -p 2203ef501040eba0 -f 0x6896000000 -t 0x6896300000 -v
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FOUND key: 689629ff1a
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Note that this is the key in reverse byte order.
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Now we can search for the passphrase using the following commandline.
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cat wordlist.txt | ./openssl_pass_crack -s 68e8f778efe0db98453532b7ede8e0c09830ec81 -k 1aff299668 -i 1 -n 1024
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FOUND key: kspass
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Instead of `cat wordlist.txt` you can use JohnTheRipper for password generation:
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john --wordlist=dict.txt --rules --stdout" | ./openssl_pass_crack ....
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