Package edu.fiu.adwise.homomorphic_encryption.dgk

Class DGKOperations

java.lang.Object

edu.fiu.adwise.homomorphic_encryption.dgk.DGKOperations

All Implemented Interfaces:

CipherConstants

public final class DGKOperations
extends Object
implements CipherConstants

DGKOperations is responsible for all the basic DGK functions. Note, we denote x, y as plaintext values and [x] and [y] as the encrypted version of x and y. The functions are: - Encrypt x -> [x] - Decrypt [x] -> x - Add two ciphertexts [x] + [y] -> [x + y] - Add a ciphertext and plaintext [x] + y -> [x + y] - Subtract two ciphertexts [x] - [y] -> [x - y] - Subtract a ciphertext and plaintext [x] - y -> [x - y] - Subtract a plaintext and ciphertext y - [x] -> [y - x] - Multiply a ciphertext and plaintext [x] * y -> [x * y] - Divide a ciphertext by plaintext [x] / y -> [x / y] THIS ONLY WORKS IF YOU KNOW YOU HAVE A PERFECT DIVISOR

Field Summary

Fields inherited from interface edu.fiu.adwise.homomorphic_encryption.misc.CipherConstants

BILLION, CERTAINTY, EIGHT, FIELD_SIZE, FIVE, FOUR, KEY_SIZE, NEG_ONE, rnd, THREE, TWO

Constructor Summary

Constructors

Constructor	Description
DGKOperations()

Method Summary

Modifier and Type	Method	Description
static BigInteger	add(BigInteger ciphertext1, BigInteger ciphertext2, DGKPublicKey public_key)	returns the sum of the two DGK encrypted values Note: The result is still encrypted Warning: If the sum exceeds N, it is subject to N
static BigInteger	add_plaintext(BigInteger ciphertext, long plaintext, DGKPublicKey public_key)	returns the sum of the DGK encrypted value and plaintext value Warning: If the sum exceeds u, it is subject to mod u
static BigInteger	add_plaintext(BigInteger ciphertext, BigInteger plaintext, DGKPublicKey public_key)	returns the sum of the DGK encrypted value and plaintext value Warning: If the sum exceeds u, it is subject to mod u
static long	decrypt(BigInteger ciphertext, DGKPrivateKey private_key)	Compute DGK decryption c = g^m * h^r (mod n) c^vp (mod p) = g^{vp*m} (mod p), Because h^{vp} (mod p) = 1 Use the pre-computed hashmap to retrieve m.
static BigInteger	divide(BigInteger ciphertext, BigInteger plaintext, DGKPublicKey public_key)	Compute the division of the DGK cipher-text and a plaintext.
static BigInteger	encrypt(long plaintext, DGKPublicKey public_key)	Encrypt plaintext with DGK Public Key Compute ciphertext = g^{m}h^{r} (mod n)
static BigInteger	encrypt(BigInteger plaintext, DGKPublicKey public_key)	Encrypt plaintext with DGK Public Key Compute ciphertext = g^{m}h^{r} (mod n)
static BigInteger	multiply(BigInteger ciphertext, long plaintext, DGKPublicKey public_key)	Compute the DGK encrypted value of ciphertext multiplied by the plaintext.
static BigInteger	multiply(BigInteger ciphertext, BigInteger plaintext, DGKPublicKey public_key)	Compute the DGK encrypted value of ciphertext multiplied by the plaintext.
static BigInteger	subtract(BigInteger ciphertext1, BigInteger ciphertext2, DGKPublicKey public_key)	Subtract ciphertext1 and ciphertext 2
static BigInteger	subtract_ciphertext(BigInteger plaintext, BigInteger ciphertext, DGKPublicKey public_key)	y - [x] = y + [-x] = [-x] + y Computes encrypted DGK value of the cipher-text subtracted by the plaintext
static BigInteger	subtract_plaintext(BigInteger ciphertext, BigInteger plaintext, DGKPublicKey public_key)	Computes encrypted DGK value of the cipher-text subtracted by the plaintext Warning: If the difference goes negative, add u.
static BigInteger	sum(BigInteger[] parts, DGKPublicKey public_key)	Compute the sum of the encrypted DGK values
static BigInteger	sum(BigInteger[] values, DGKPublicKey public_key, int limit)	Compute the sum of the encrypted DGK values
static BigInteger	sum(List<BigInteger> values, DGKPublicKey public_key)	Compute the sum of the encrypted DGK values
static BigInteger	sum(List<BigInteger> values, DGKPublicKey public_key, int limit)	Compute the sum of the encrypted DGK values
static BigInteger	sum_product(BigInteger[] ciphertext, Long[] plaintext, DGKPublicKey public_key)	Compute the sum-product.
static BigInteger	sum_product(List<BigInteger> ciphertext, List<Long> plaintext, DGKPublicKey public_key)	Compute the sum-product.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

DGKOperations

public DGKOperations()

Method Details

encrypt

public static BigInteger encrypt(long plaintext,
 DGKPublicKey public_key)
                          throws HomomorphicException

Encrypt plaintext with DGK Public Key Compute ciphertext = g^{m}h^{r} (mod n)

Parameters:

plaintext - - plaintext value to be encrypted

public_key - - use this to encrypt plaintext

Returns:

- DGK ciphertext of the plaintext

Throws:

HomomorphicException - - If the plaintext is larger than the plaintext supported by DGK Public Key an exception will be thrown

encrypt

public static BigInteger encrypt(BigInteger plaintext,
 DGKPublicKey public_key)
                          throws HomomorphicException

Encrypt plaintext with DGK Public Key Compute ciphertext = g^{m}h^{r} (mod n)

Parameters:

plaintext - - plaintext value to be encrypted

public_key - - use this to encrypt plaintext

Returns:

- DGK ciphertext of the plaintext

Throws:

HomomorphicException - - If the plaintext is larger than the plaintext supported by DGK Public Key an exception will be thrown

decrypt

public static long decrypt(BigInteger ciphertext,
 DGKPrivateKey private_key)
                    throws HomomorphicException

Compute DGK decryption c = g^m * h^r (mod n) c^vp (mod p) = g^{vp*m} (mod p), Because h^{vp} (mod p) = 1 Use the pre-computed hashmap to retrieve m.

Parameters:

ciphertext - - DGK ciphertext

private_key - - used to decrypt ciphertext

Returns:

plaintext

Throws:

HomomorphicException - - If the ciphertext is larger than the ciphertext supported by DGK Public Key an exception will be thrown

add

public static BigInteger add(BigInteger ciphertext1,
 BigInteger ciphertext2,
 DGKPublicKey public_key)
                      throws HomomorphicException

returns the sum of the two DGK encrypted values Note: The result is still encrypted Warning: If the sum exceeds N, it is subject to N

Parameters:

ciphertext1 - - Encrypted DGK value

ciphertext2 - - Encrypted DGK value

public_key - - used to encrypt both ciphertexts

Returns:

the encrypted sum of both DGK encrypted values

Throws:

HomomorphicException - - If either ciphertext is greater than N or negative, throw an exception

add_plaintext

public static BigInteger add_plaintext(BigInteger ciphertext,
 BigInteger plaintext,
 DGKPublicKey public_key)
                                throws HomomorphicException

returns the sum of the DGK encrypted value and plaintext value Warning: If the sum exceeds u, it is subject to mod u

Parameters:

ciphertext - - DGK encrypted value

plaintext - - plaintext value

public_key - - was used to encrypt ciphertext

Returns:

Encrypted sum of ciphertext and plaintext

Throws:

HomomorphicException - - If a ciphertext is negative or exceeds N, or plaintext is negative or exceeds u

add_plaintext

public static BigInteger add_plaintext(BigInteger ciphertext,
 long plaintext,
 DGKPublicKey public_key)
                                throws HomomorphicException

returns the sum of the DGK encrypted value and plaintext value Warning: If the sum exceeds u, it is subject to mod u

Parameters:

ciphertext - - DGK encrypted value

plaintext - - plaintext value

public_key - - was used to encrypt ciphertext

Returns:

Encrypted sum of ciphertext and plaintext

Throws:

HomomorphicException - - If a ciphertext is negative or exceeds N, or plaintext is negative or exceeds u

subtract

public static BigInteger subtract(BigInteger ciphertext1,
 BigInteger ciphertext2,
 DGKPublicKey public_key)
                           throws HomomorphicException

Subtract ciphertext1 and ciphertext 2

Parameters:

ciphertext1 - - Encrypted DGK value

ciphertext2 - - Encrypted DGK value

public_key - - used to encrypt both ciphertexts

Returns:

DGK encrypted ciphertext with ciphertext1 - ciphertext2

Throws:

HomomorphicException - - If an invalid input was found

subtract_plaintext

public static BigInteger subtract_plaintext(BigInteger ciphertext,
 BigInteger plaintext,
 DGKPublicKey public_key)
                                     throws HomomorphicException

Computes encrypted DGK value of the cipher-text subtracted by the plaintext Warning: If the difference goes negative, add u.

Parameters:

ciphertext - - Encrypted DGK value

plaintext - - plaintext value

public_key - - used to encrypt ciphertext

Returns:

DGK encrypted ciphertext with ciphertext1 - ciphertext2

Throws:

HomomorphicException - - If an invalid input was found

subtract_ciphertext

public static BigInteger subtract_ciphertext(BigInteger plaintext,
 BigInteger ciphertext,
 DGKPublicKey public_key)
                                      throws HomomorphicException

y - [x] = y + [-x] = [-x] + y Computes encrypted DGK value of the cipher-text subtracted by the plaintext

Parameters:

plaintext - - plaintext value

ciphertext - - Encrypted DGK value

public_key - - used to encrypt ciphertext

Returns:

DGK encrypted ciphertext with plaintext - ciphertext

Throws:

HomomorphicException - - If an invalid input was found

multiply

public static BigInteger multiply(BigInteger ciphertext,
 BigInteger plaintext,
 DGKPublicKey public_key)
                           throws HomomorphicException

Compute the DGK encrypted value of ciphertext multiplied by the plaintext.

Parameters:

ciphertext - - DGK encrypted value

plaintext - - plaintext value

public_key - - DGK Public key the encrypted ciphertext

Returns:

product - the encrypted product of the ciphertext and the plaintext

Throws:

HomomorphicException - - If ciphertext is negative or exceeds N or plaintext exceeds u

multiply

public static BigInteger multiply(BigInteger ciphertext,
 long plaintext,
 DGKPublicKey public_key)
                           throws HomomorphicException

Compute the DGK encrypted value of ciphertext multiplied by the plaintext.

Parameters:

ciphertext - - DGK encrypted value

plaintext - - plaintext value

public_key - - DGK Public key the encrypted ciphertext

Returns:

product - the encrypted product of ciphertext and the plaintext value

Throws:

HomomorphicException - - If ciphertext is negative or exceeds N or plaintext exceeds u

divide

public static BigInteger divide(BigInteger ciphertext,
 BigInteger plaintext,
 DGKPublicKey public_key)
                         throws HomomorphicException

Compute the division of the DGK cipher-text and a plaintext. Warning: Divide will only work correctly on perfect divisor like 2|20, it will work. If you try 3|20, it will NOT work, and you will get a wrong answer! If you want to do 3|20, you MUST use a division protocol from Veugen paper

Parameters:

ciphertext - - DGK ciphertext

plaintext - -plaintext value

public_key - - was used to encrypt ciphertext

Returns:

Encrypted DGK value equal to ciphertext/plaintext

Throws:

HomomorphicException - - If an invalid input was found

sum

public static BigInteger sum(BigInteger[] parts,
 DGKPublicKey public_key)
                      throws HomomorphicException

Compute the sum of the encrypted DGK values

Parameters:

parts - - Array of Encrypted DGK values

public_key - - DGKPublicKey used to encrypt all the values

Returns:

sum - the encrypted sum of all encrypted values in the array

Throws:

HomomorphicException - - If an invalid input was found

sum

public static BigInteger sum(BigInteger[] values,
 DGKPublicKey public_key,
 int limit)
                      throws HomomorphicException

Compute the sum of the encrypted DGK values

Parameters:

values - - Array of Encrypted DGK values

public_key - - DGKPublicKey used to encrypt the values

limit - - Sum values up to this index value in the list

Returns:

sum - the encrypted sum of all values in the array

Throws:

HomomorphicException - - If an invalid input was found

sum

public static BigInteger sum(List<BigInteger> values,
 DGKPublicKey public_key)
                      throws HomomorphicException

Compute the sum of the encrypted DGK values

Parameters:

values - - List of Encrypted DGK values

public_key - - DGKPublicKey used to encrypt the values

Returns:

sum - the encrypted sum of all values in the list

Throws:

HomomorphicException - - If an invalid input was found

sum

public static BigInteger sum(List<BigInteger> values,
 DGKPublicKey public_key,
 int limit)
                      throws HomomorphicException

Compute the sum of the encrypted DGK values

Parameters:

values - - List of Encrypted DGK values

public_key - - DGKPublicKey used to encrypt the values

limit - - Sum values up to this index value in the list

Returns:

sum - the encrypted sum of all values in the list

Throws:

HomomorphicException - - If an invalid input was found

sum_product

public static BigInteger sum_product(List<BigInteger> ciphertext,
 List<Long> plaintext,
 DGKPublicKey public_key)
                              throws HomomorphicException

Compute the sum-product. It computes the scalar multiplication between the array of Encrypted and plaintext values. Then it computes the encrypted sum.

Parameters:

ciphertext - - List of Encrypted DGK values

plaintext - - List of Encrypted DGK values

public_key - - DGK Public Key used to encrypt list of ciphertext

Returns:

DGK Encrypted sum product

Throws:

HomomorphicException - - If an invalid input was found

sum_product

public static BigInteger sum_product(BigInteger[] ciphertext,
 Long[] plaintext,
 DGKPublicKey public_key)
                              throws HomomorphicException

Compute the sum-product. It computes the scalar multiplication between the array of Encrypted and plaintext values. Then it computes the encrypted sum.

Parameters:

ciphertext - - Array of Encrypted DGK values

plaintext - - Array of Plaintext values

public_key - - DGK Public Key used to encrypt values in a ciphertext list

Returns:

DGK Encrypted sum-product

Throws:

HomomorphicException - - If the size of plaintext array and ciphertext array isn't equal