wie ssh-rsa öffentlichen Schlüssel PEM PKCS # 1 Public-Key-Format mit Java 7

Question

My Public in ssh-rsa ist zu konvertieren:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQClAxT5S/WuX04OXBt9R59WcL45OmaU3M5U063lfyja7ovqaVR7/2kHtLF/LoCQCXSZMny8RTCGDjoXD7G/tGsyHFDHCI // Y1VDLE06AlDzrlu69DQY91 + 6gkhGjH3SF6us5hXlihrbSFLfAlSdkEs8gwSrspVQyuaOf + 39dnMddhEDYYg + z0ce82ta/n8xPBWCp60nDEDayNjOsRgzDJKSujNfngjQTL1x6qKJj8BW/P5lLJE1nbMm9BQD9G7glJk86qh1I/tJCnij6On0m6KcdzVz8cU3sBgNeB433kGjJtpxXXmJB6Vuu5IverhyfpiB4hP9WlKa/LSzW + ZIdvl/

wollte ich es PKCS # 1 unten Format konvertieren

----- BEGIN RSA PUBLI C KEY ----- MIIBCgKCAQEAoL7K8ijUPfkkpdiIMIoHxzTn + npLzJGHr7QO09Mnz8Q1xFfv9Arr 3Eg2R7LdTMJ + v2Rk3EDRGJEwK8cWv5Hvh7KXIdRqtw2ouxY6pK9RXfvaQ0CF2nI9 Y7VxASdOvnI8byzlw9SvR1eDjpzIh8/wtz3KcJK5aCRsAyH6ddvM4tPisQaKVBGN nCtPq94PspbpEYbNSQXTmnpO099P99oDXT + kpCaNrPvM5xWmUj0R7UwbmYYdNnVB UPFTKj + qVpp8TUTFUgk8noke7ABK6tncf8wmB8mPhgoKznZP5MaLZpB1f4gBeXst GNiLN4LwgRSM56eCEVqQHkVRuRrM9nODWQIDAQAB

----- END öffentlichen RSA-Schlüssel -----

Inhaltsangabe: Ich möchte Datei mit dem obigen öffentlichen Schlüssel in Java 7 überprüfen, wie ich mit dem ungültigen Schlüssel Formatfehler für ssh-rsa öffentlichen Schlüssel konfrontiert bin bitte lassen Sie mich wissen, was muss getan werden.

Sie weiter unten finden Snippet:

byte[] decoded; 
     try { 
     decoded = Base64.getDecoder().decode(publickeyStr); 
     org.bouncycastle.asn1.pkcs.RSAPublicKey pkcs1PublicKey = org.bouncycastle.asn1.pkcs.RSAPublicKey.getInstance(decoded); 
     BigInteger modulus = pkcs1PublicKey.getModulus(); 
     BigInteger publicExponent = pkcs1PublicKey.getPublicExponent(); 
     RSAPublicKeySpec keySpec = new RSAPublicKeySpec(modulus, publicExponent); 
     KeyFactory kf; 
     kf = KeyFactory.getInstance("RSA"); 
     PublicKey generatedPublic = kf.generatePublic(keySpec); 
     System.out.printf("Modulus: %X%n", modulus); 
     System.out.printf("Public exponent: %d ... 17? Why?%n", publicExponent); 
     System.out.printf("See, Java class result: %s, is RSAPublicKey: %b%n", generatedPublic.getClass().getName(), generatedPublic instanceof RSAPublicKey); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

es unter Ausnahme geben:

java.lang.IllegalArgumentException: Illegal base64 character 2d 
    at java.util.Base64$Decoder.decode0(Base64.java:714) 
    at java.util.Base64$Decoder.decode(Base64.java:526) 
    at java.util.Base64$Decoder.decode(Base64.java:549) 
    at SignVerify.convertPublicPKCS1StrToPKCS8PublicKeyObj(SignVerify.java:136) 
    at SignVerify.main(SignVerify.java:184) 

Answer 1

Ich finde kein Werkzeug oder Lösungen in Java, die es tun können. Also, ich lese RFC 4253 für Public Key Formatbeschreibung und RFC 4251 für mpint Beschreibung. Wichtige Teile von RFC 4253. Abschnitt 6,6

The "ssh-rsa" key format has the following specific encoding: 

    string "ssh-rsa" 
    mpint  e 
    mpint  n 

Here the 'e' and 'n' parameters form the signature key blob. 

und wichtiger Bestandteil von RFC 4251

mpint 

    Represents multiple precision integers in two's complement format, 
    stored as a string, 8 bits per byte, MSB first. Negative numbers 
    have the value 1 as the most significant bit of the first byte of 
    the data partition. If the most significant bit would be set for 
    a positive number, the number MUST be preceded by a zero byte. 
    Unnecessary leading bytes with the value 0 or 255 MUST NOT be 
    included. The value zero MUST be stored as a string with zero 
    bytes of data. 

    By convention, a number that is used in modular computations in 
    Z_n SHOULD be represented in the range 0 <= x < n. 

    Examples: 

    value (hex)  representation (hex) 
    -----------  -------------------- 
    0     00 00 00 00 
    9a378f9b2e332a7 00 00 00 08 09 a3 78 f9 b2 e3 32 a7 
    80     00 00 00 02 00 80 
    -1234    00 00 00 02 ed cc 
    -deadbeef   00 00 00 05 ff 21 52 41 11 

all dies wissen, Code schreiben, ssh-rsa Schlüssel zum Java-Format ist einfach zu konvertieren.

private static int SIZEOF_INT = 4; 
private static String key1 = "AAAAB3NzaC1yc2EAAAADAQABAAABAQClAxT5S/WuX04OXBt9R59WcL45OmaU3M5U063lfyja7ovqaVR7/2kHtLF/LoCQCXSZMny8RTCGDjoXD7G/tGsyHFDHCI//Y1VDLE06AlDzrlu69DQY91+6gkhGjH3SF6us5hXlihrbSFLfAlSdkEs8gwSrspVQyuaOf+39dnMddhEDYYg+z0ce82ta/n8xPBWCp60nDEDayNjOsRgzDJKSujNfngjQTL1x6qKJj8BW/P5lLJE1nbMm9BQD9G7glJk86qh1I/tJCnij6On0m6KcdzVz8cU3sBgNeB433kGjJtpxXXmJB6Vuu5IverhyfpiB4hP9WlKa/LSzW+ZIdvl/"; 

@Test 
public void convertkey() throws Exception { 
    byte[] decoded = java.util.Base64.getDecoder().decode(key1); 

    try { 
     ByteBuffer byteBuffer = ByteBuffer.wrap(decoded); 

     AtomicInteger position = new AtomicInteger(); 
     //first read algorithm, should be ssh-rsa 
     String algorithm = readString(byteBuffer, position); 
     System.out.println(algorithm); 
     assert "ssh-rsa".equals(algorithm); 
     // than read exponent 
     BigInteger publicExponent = readMpint(byteBuffer, position); 
     System.out.println("publicExponent = " + publicExponent); 
     // than read modulus 
     BigInteger modulus = readMpint(byteBuffer, position); 
     System.out.println("modulus = " + modulus); 
     RSAPublicKeySpec keySpec = new RSAPublicKeySpec(modulus, publicExponent); 
     KeyFactory kf = KeyFactory.getInstance("RSA"); 
     PublicKey publicKey = kf.generatePublic(keySpec); 

     System.out.printf("Modulus: %X%n", modulus); 
     System.out.printf("Public exponent: %d ... 17? Why?%n", publicExponent); 
     System.out.printf("See, Java class result: %s, is RSAPublicKey: %b%n", publicKey.getClass().getName(), publicKey instanceof RSAPublicKey); 

     byte[] pubBytes = publicKey.getEncoded(); 

     SubjectPublicKeyInfo spkInfo = SubjectPublicKeyInfo.getInstance(pubBytes); 
     ASN1Primitive primitive = spkInfo.parsePublicKey(); 
     writePEM("pubPkcs1.pem", "RSA PUBLIC KEY", primitive.getEncoded()); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

} 

private BigInteger readMpint(ByteBuffer buffer, AtomicInteger pos){ 
    byte[] bytes = readBytes(buffer, pos); 
    if(bytes.length == 0){ 
     return BigInteger.ZERO; 
    } 
    return new BigInteger(bytes); 
} 

private String readString(ByteBuffer buffer, AtomicInteger pos){ 
    byte[] bytes = readBytes(buffer, pos); 
    if(bytes.length == 0){ 
     return ""; 
    } 
    return new String(bytes, StandardCharsets.US_ASCII); 
} 

private byte[] readBytes(ByteBuffer buffer, AtomicInteger pos){ 
    int len = buffer.getInt(pos.get()); 
    byte buff[] = new byte[len]; 
    for(int i = 0; i < len; i++) { 
     buff[i] = buffer.get(i + pos.get() + SIZEOF_INT); 
    } 
    pos.set(pos.get() + SIZEOF_INT + len); 
    return buff; 
} 

private void writePEM(String fileName, String header, byte[] content) throws IOException{ 
    File f = new File(fileName); 
    FileWriter fw = new FileWriter(f); 
    PemObject pemObject = new PemObject(header, content); 
    PemWriter pemWriter = new PemWriter(fw); 
    pemWriter.writeObject(pemObject); 
    pemWriter.close(); 
} 

Ausgang

ssh-rsa 
publicExponent = 65537 
modulus = 20830840075214895520187085209140532093913000825284169131015003256319574044057453999265862514662442478787476545768050679936827456316397871442660366713280574836948529205417590573371022714192162142283026905055750951413644811120376414428742776306570652231542058994893537065648692533801879404176161589597321580633083481631733302249100913607754671673449460161582195402470090670605789220193388312197339358656479303453367386441996440265509774568364904443092245613429875362588897307051303623648237031289817493491475305022256278911859470009225208699382584578527080735302630318546541433464398236590978005758010444925861059033471 
Modulus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
Public exponent: 65537 ... 17? Why? 
See, Java class result: sun.security.rsa.RSAPublicKeyImpl, is RSAPublicKey: true 

Zweite Teil - Java-Objekt als PKCS1 öffentlicher Schlüssel speichern.

Wenn Sie pubkeys.getEncoded() schreiben, haben Sie den öffentlichen Schlüssel pkcs8, der öffentliche RSA-Schlüssel ist anders. Format beschrieben in RFC 3447 Anhang A.1.1

An RSA public key should be represented with the ASN.1 type 
RSAPublicKey: 

    RSAPublicKey ::= SEQUENCE { 
     modulus   INTEGER, -- n 
     publicExponent INTEGER -- e 
    } 

The fields of type RSAPublicKey have the following meanings: 
* modulus is the RSA modulus n. 
* publicExponent is the RSA public exponent e. 

This question am besonders Ian Boyd Antwort gibt viele Details.

Hüpfburg hat bereits die Klasse SubjectPublicKeyInfo, um mit dieser Situation umzugehen.

byte[] pubBytes = publicKey.getEncoded(); 
//writePEM("pubPkcs8.pem", "PUBLIC KEY", pubBytes); // if you need pkcs8  
SubjectPublicKeyInfo spkInfo = SubjectPublicKeyInfo.getInstance(pubBytes); 
ASN1Primitive primitive = spkInfo.parsePublicKey(); 
writePEM("pubPkcs1.pem", "RSA PUBLIC KEY", primitive.getEncoded()); 

Inhalt pubPkcs1.pem

-----BEGIN RSA PUBLIC KEY----- 
MIIBCgKCAQEApQMU+Uv1rl9ODlwbfUefVnC+OTpmlNzOVNOt5X8o2u6L6mlUe/9p 
B7Sxfy6AkAl0mTJ8vEUwhg46Fw+xv7RrMhxQxwiP/2NVQyxNOgJQ865buvQ0GPdf 
uoJIRox90herrOYV5Yoa20hS3wJUnZBLPIMEq7KVUMrmjn/t/XZzHXYRA2GIPs9H 
HvNrWv5/MTwVgqetJwxA2sjYzrEYMwySkrozX54I0Ey9ceqiiY/AVvz+ZSyRNZ2z 
JvQUA/Ru4JSZPOqodSP7SQp4o+jp9JuinHc1c/HFN7AYDXgeN95BoybacV15iQel 
bruSL3q4cn6YgeIT/VpSmvy0s1vmSHb5fwIDAQAB 
-----END RSA PUBLIC KEY----- 

Überprüfung Ergebnisse mit openssl

$ openssl asn1parse -in pubPkcs1.pem 
0:d=0 hl=4 l= 266 cons: SEQUENCE   
4:d=1 hl=4 l= 257 prim: INTEGER   :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 
265:d=1 hl=2 l= 3 prim: INTEGER   :010001