Public Key Infrastructures

Transcription

1 Public Key Infrastructures How to store private keys? Chapter 6 Private Keys Cryptography and Computeralgebra Vangelis Karatsiolis 1 2 Personal Security Environment (PSE) Realisation of PSEs : Tokens Secure storing of private keys Private keys are stored in PSEs in Software in Hardware PKCS#12 Java KeyStore Application specific (e.g. Netscape) USB-Token Smartcard Hardware Security Module (HSM) 3 4 Token properties PKCS#12 Compatibility Portability Availability Access protection Software based PSE Format for secure transport and storing Most typical format for software PSEs Available at: 5 6

2 PKCS#12: Modes PKCS#12: Structure Public Key Privacy Mode: Encryption with a symmetric key. This symmetric key is encrypted with the public key of the receiver. Password Privacy Mode: Encryption with one symmetric key, which is derived from a password. Public Key Integrity Mode: Signed with a private key. The receiver can verify the message. Password Integrity Mode: A MAC is calculated which can be verified by the receiver. AuthenticatedSafe ContentInfo Plain Data Encrypted Data Enveloped data 7 8 Example Personal nformation Exchange Password: Java Keystores Implementation of the KeyStore Class Two types: JKS Proprietary algorithms Weak encryption JCEKS Standard algorithms Strong encryption Part of the JCE (Java Cryptography Extensions) Since Java 1.4 KeyStore example keytool -genkey -alias test -keyalg RSA -keysize keypass storepass keystore test.ks Run:../Certificates/keytool.bat Sign with the keystore: Run:../Certificates/keytoolSign.bat Easy Administration with keytool 11 12

3 Application specific Private key import in Firefox Examples: Mozilla Windows Private key access in Firefox Private key import in Windows Private key access in Windows Application specific Netscape Family Mozilla, Firefox, Thunderbird, SeaMonkey Through Software Security Module The standard implementation is proprietary The format for the import is PKCS#12 Windows Internet Explorer, Outlook/Express The standard implementation is proprietary Through Cryptographic Service Provider The format for the import is PKCS#

4 Hardware Security Module Hardware Security Module Protect the keys against Mechanical attacks Secure storing and use of keys Pseudorandom number generation Key pair generation Calculation of digital signatures Key archiving Acceleration for cryptographic schemes Temperature attacks Manipulation of the voltage Chemical attacks The keys are destroyed in case of danger Hardware Security Module Smartcards But Keys can be accidentally destroyed e.g. due to mechanical influence during transport Reduced number of keys Secure key storing and use Key pair generation (not all) Calculation of digital signatures Decryption Interface to the card Access over PKCS#11 Support functions like: Change PIN, Sign, Decrypt, Write certificate But: Some functions are not supported (e.g. change PUK) Possibly many libraries are needed for supporting different cards and readers. Available at: Access over PKCS#15 Specifies the structure of the card in the card Every directory in the card is an application Pointers to cryptographic objekts (ODF) PrivateKey PublicKey Certificate Available at:

5 Structure PKCS#15 E4 NetKey (TeleSec) ODF Descriptor DF(PKCS#15) PrKDF CDF MasterFile rdata EF (DIR) ADF TokenInfo Pointer to PrivateKey Data, Certificate Data, Authentication Data (PIN) and Token Information (Serial number) Furter DFs/EFs E4 evaluated (according to ITSEC) Global files (serial number, etc.) SigG application Pre-keyd with one key-pair according to SigG (Signature Act) NetKey application 3 key pairs (pre-keyed) Null-PIN scheme (patented) Java Cards No filesystem but applets JCRE (Java Card Runtime Environment) manages: the resources of the card the communication with the outside world the execution of the applets controls: the compliance with the security limitations Java Cards Like normal Java code but No long, double, float Characters and Strings Multidimensional arrays Threads Object serialisation und cloning Dynamic loading of classes (like drivers) Security Manager Garbage Collector not always present Examples Life cycle of private keys Of secure signature-creation devices storing Secure signature-creation devices start state state end state 29 30

6 Life cycle of private keys Life cycle of private keys Storing Storing appropriate parameters persistent storing secure random number generator shielding against eavesdropping deletion from the generator appropriate access protection Life cycle of private keys Life cycle of private keys Storing Storing correct receiver easy for the authorised users guaranteed delivery appropriate transport security mechanisms 33 impossible for the unauthorised users protection of the private key 34 Life cycle of private keys Life cycle of private keys Storing Storing unrecoverable persistent storing easy for authorised users only for certain keys impossible for unauthorised users 35 appropriate access protection 36

7 Life cycle of private keys r generates key Storing PGP Example correct reestablishment easy for authorised users impossible for unauthorised users

8 Storing 47 48

9 File contents../certificates/test r.cxt

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11 61 62 Trust center generates key The manufacturer creates the keys Trust center example TUDCard input 63 output 64 Storing By snail mail Contains the private key A file exists that holds the private key. Security condition: PSO (Perform Security Operation) after PIN has been correctly given

12 First detection Null-PIN technique PIN-Entry necessary for PSO Set PIN See PUK Download certificate Physical destruction of the card. high temperature, etc Every key is stored in a PKCS#12 file An example TUDCardKey input output 71 72

13 r generates key Generate The user generates its own private key keytool -genkey -keyalg RSA -keystore keystore.ks -alias myalias Store keytool -genkey -keyalg RSA -keystore keystore.ks -alias myalias The key is already at the client side In order to use the private key, the public key is certified by a CA. Thawte example 77 78

14 Hi! Please use your browser to go to the following URL: Once you have connected successfully to the above address, you must copy and paste the "probe" and "ping" values below into the appropriate text boxes: Probe: value Ping: value You should save this message until you have completed the enrollment process, just in case. But you MUST go to the above URL within 24 hours, or we will delete your request information and you'll have to start over! If you have problems completing the above please contact our support team by going to the following URL: Regards, The thawte team thawte Certification 83 84

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16 address keytool -certreq -keystore keystore.ks -file csr.txt -alias myalias BEGIN NEW CERTIFICATE REQUEST----- MIIBrDCCARUCAQwbDELMAkGA1UEBhMCREUxDjAMBgNVB TBUhlc3NlMRIwEAYDVQQHEwlEYXJtN57qbnyAfAAAAAAA c3rhzhqxddkbgnvata1rvrdemmaoga1uecxmdq0rdmr wgwydvqqdexrwy5nzwxpcyblyxjhn57qbnyafaaaaaaa dhnpb2xpcznzanbqhkig9w0baqefaaobjqawgykcgyearoj ITHFBR5orQ9dB4qkP/gMhS1hCNiowdM2CrJINiowdM2CCCCE +Qrzut77pzzjlEBLQeeMC0Q88LF8tTJfFoUKdGni/PAAiOPHxv NXFFH0YZs4/P7gXMAX+9eEgGNiowdM2CrJINiowdM2CCCCE jl2ig7pyqlkggwibvxyqmex2tkk9tkwqcvfjl6bktjiijermgoly i79dk3cdwx26z8caweaaaaaniowdm2crjiniowdm2cccceee MA0GCSqGSIb3DEBBAUAAGBAIvbaheW+lVaDdRN57qbnyAf3 qqxd2gcjmbccco8v3tn9zc4mseniowdm2crjiniowdm2cccc pxxtfqg4uqo0urjiniowdm2ctrpzletorjntoxxirlhp9+lln XnER43nYvcLZ/QIChlfIX6KiPrJINiowdM2CrJINiowdM2CCCC Elr81bvYRq6G/bGxrz4K55c17UIqPtlGN7yQEDxYZ5e END NEW CERTIFICATE REQUEST

17 97 98 The user receives a URL that contains the certificate inside a PKCS#7 structure keytool -import -file test.crt -alias myalias -trustcacerts -keystore keystore.ks

18 A simple copy of the file to: a CD a USB stick an external hard disc or similar from the copy location. Password is needed. The password may be changed