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Are DSA and ECDSA provably secure assuming DL security?


DSA, RSA, ECDSA etc - which one is cheapest for signing?Verifying DER encoded DSA/ECDSA signature with extra content?Can Alice send Bob a secure message with only DSA and no key exchange?Cost of attack on DSA with attack on DLPWhat is the intuition for ECDSA?How does the “biased-$k$ attack” on (EC)DSA work?Why is ECDSA secure?Is it actually possible to secure data with gpg DSA keys?Group signatures, security and ECDSASecurity of Fast Two-Party ECDSA Signing













5












$begingroup$


Is there proof that the DSA construction, also used by ECDSA, is secure assuming that discrete logarithms in the relevant group representation are difficult?










share|improve this question









$endgroup$

















    5












    $begingroup$


    Is there proof that the DSA construction, also used by ECDSA, is secure assuming that discrete logarithms in the relevant group representation are difficult?










    share|improve this question









    $endgroup$















      5












      5








      5





      $begingroup$


      Is there proof that the DSA construction, also used by ECDSA, is secure assuming that discrete logarithms in the relevant group representation are difficult?










      share|improve this question









      $endgroup$




      Is there proof that the DSA construction, also used by ECDSA, is secure assuming that discrete logarithms in the relevant group representation are difficult?







      provable-security dsa






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 9 hours ago









      MyriaMyria

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      948414






















          1 Answer
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          4












          $begingroup$

          (The (EC)DSA algorithm involves two functions: (i) the "conversion function" $f$, which for the case of DSA is a modulo $q$ operation and for ECDSA is the modulo $q$ operation applied to the $x$-coordinate of the input point; and (ii) $H$ a cryptographic hash function applied to the message.)



          Brown [B] showed that the DLP implies security of ECDSA in the generic group model and under idealised modelling of the conversion function $f$. The second assumption is in particular unrealistic as in (EC)DSA it is implemented by a simple modulo operation.



          There have been some recent results by Fersch et al. [FKP1,FKP2] which have tried to relax the above assumptions. In [FKP1] it is shown that under weaker (but still quite strong) assumption on the conversion function $f$ (and under some reasonable assumption on the hash function $H$) that DLP implies the security of (EC)DSA. Perhaps the security argument with the most reasonable assumptions is given in [FKP2]. There, assuming that the hash function $H$ is modelled as a random oracle, and the signer issues at most one signature per message, then EC(DSA) is unforgeable if and only if they are key-only unforgeable (this applies also to other schemes like the Russian GOST 34.14 and the Chinese SM2). It is not known if the key-only security of (EC)DSA reduces to DLP.



          So, in short, the answer would be no, not under reasonable assumptions.



          (Note however, that there are close variants of the (EC)DSA, most notably the Schnorr signature and the scheme by Brickell et al [B+] which do come with security reductions in the random oracle model. Also it is baffling why (EC)DSA is still in use since the patent on Schnorr expired in 2008.)



          [B] Brown. Generic Groups, Collision Resistance and ECDSA.



          [B+] Brickell et al. Design validations for discrete logarithm based signature schemes. PKC'00.



          [FKP1] Fersch, Kiltz and Pöttering. On the Provable Security of (EC)DSA Signatures. CCS'16.



          [FKP2] Fersch, Kiltz and Pöttering. On the One-Per-Message Unforgeability of (EC)DSA and its Variants. TCC'17.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Your answer is better than mine was.
            $endgroup$
            – fgrieu
            8 hours ago










          • $begingroup$
            Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
            $endgroup$
            – Myria
            8 hours ago










          • $begingroup$
            That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
            $endgroup$
            – Occams_Trimmer
            8 hours ago












          • $begingroup$
            As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
            $endgroup$
            – grawity
            3 mins ago












          Your Answer








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          1 Answer
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          active

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          1 Answer
          1






          active

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          active

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          active

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          4












          $begingroup$

          (The (EC)DSA algorithm involves two functions: (i) the "conversion function" $f$, which for the case of DSA is a modulo $q$ operation and for ECDSA is the modulo $q$ operation applied to the $x$-coordinate of the input point; and (ii) $H$ a cryptographic hash function applied to the message.)



          Brown [B] showed that the DLP implies security of ECDSA in the generic group model and under idealised modelling of the conversion function $f$. The second assumption is in particular unrealistic as in (EC)DSA it is implemented by a simple modulo operation.



          There have been some recent results by Fersch et al. [FKP1,FKP2] which have tried to relax the above assumptions. In [FKP1] it is shown that under weaker (but still quite strong) assumption on the conversion function $f$ (and under some reasonable assumption on the hash function $H$) that DLP implies the security of (EC)DSA. Perhaps the security argument with the most reasonable assumptions is given in [FKP2]. There, assuming that the hash function $H$ is modelled as a random oracle, and the signer issues at most one signature per message, then EC(DSA) is unforgeable if and only if they are key-only unforgeable (this applies also to other schemes like the Russian GOST 34.14 and the Chinese SM2). It is not known if the key-only security of (EC)DSA reduces to DLP.



          So, in short, the answer would be no, not under reasonable assumptions.



          (Note however, that there are close variants of the (EC)DSA, most notably the Schnorr signature and the scheme by Brickell et al [B+] which do come with security reductions in the random oracle model. Also it is baffling why (EC)DSA is still in use since the patent on Schnorr expired in 2008.)



          [B] Brown. Generic Groups, Collision Resistance and ECDSA.



          [B+] Brickell et al. Design validations for discrete logarithm based signature schemes. PKC'00.



          [FKP1] Fersch, Kiltz and Pöttering. On the Provable Security of (EC)DSA Signatures. CCS'16.



          [FKP2] Fersch, Kiltz and Pöttering. On the One-Per-Message Unforgeability of (EC)DSA and its Variants. TCC'17.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Your answer is better than mine was.
            $endgroup$
            – fgrieu
            8 hours ago










          • $begingroup$
            Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
            $endgroup$
            – Myria
            8 hours ago










          • $begingroup$
            That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
            $endgroup$
            – Occams_Trimmer
            8 hours ago












          • $begingroup$
            As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
            $endgroup$
            – grawity
            3 mins ago
















          4












          $begingroup$

          (The (EC)DSA algorithm involves two functions: (i) the "conversion function" $f$, which for the case of DSA is a modulo $q$ operation and for ECDSA is the modulo $q$ operation applied to the $x$-coordinate of the input point; and (ii) $H$ a cryptographic hash function applied to the message.)



          Brown [B] showed that the DLP implies security of ECDSA in the generic group model and under idealised modelling of the conversion function $f$. The second assumption is in particular unrealistic as in (EC)DSA it is implemented by a simple modulo operation.



          There have been some recent results by Fersch et al. [FKP1,FKP2] which have tried to relax the above assumptions. In [FKP1] it is shown that under weaker (but still quite strong) assumption on the conversion function $f$ (and under some reasonable assumption on the hash function $H$) that DLP implies the security of (EC)DSA. Perhaps the security argument with the most reasonable assumptions is given in [FKP2]. There, assuming that the hash function $H$ is modelled as a random oracle, and the signer issues at most one signature per message, then EC(DSA) is unforgeable if and only if they are key-only unforgeable (this applies also to other schemes like the Russian GOST 34.14 and the Chinese SM2). It is not known if the key-only security of (EC)DSA reduces to DLP.



          So, in short, the answer would be no, not under reasonable assumptions.



          (Note however, that there are close variants of the (EC)DSA, most notably the Schnorr signature and the scheme by Brickell et al [B+] which do come with security reductions in the random oracle model. Also it is baffling why (EC)DSA is still in use since the patent on Schnorr expired in 2008.)



          [B] Brown. Generic Groups, Collision Resistance and ECDSA.



          [B+] Brickell et al. Design validations for discrete logarithm based signature schemes. PKC'00.



          [FKP1] Fersch, Kiltz and Pöttering. On the Provable Security of (EC)DSA Signatures. CCS'16.



          [FKP2] Fersch, Kiltz and Pöttering. On the One-Per-Message Unforgeability of (EC)DSA and its Variants. TCC'17.






          share|improve this answer











          $endgroup$













          • $begingroup$
            Your answer is better than mine was.
            $endgroup$
            – fgrieu
            8 hours ago










          • $begingroup$
            Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
            $endgroup$
            – Myria
            8 hours ago










          • $begingroup$
            That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
            $endgroup$
            – Occams_Trimmer
            8 hours ago












          • $begingroup$
            As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
            $endgroup$
            – grawity
            3 mins ago














          4












          4








          4





          $begingroup$

          (The (EC)DSA algorithm involves two functions: (i) the "conversion function" $f$, which for the case of DSA is a modulo $q$ operation and for ECDSA is the modulo $q$ operation applied to the $x$-coordinate of the input point; and (ii) $H$ a cryptographic hash function applied to the message.)



          Brown [B] showed that the DLP implies security of ECDSA in the generic group model and under idealised modelling of the conversion function $f$. The second assumption is in particular unrealistic as in (EC)DSA it is implemented by a simple modulo operation.



          There have been some recent results by Fersch et al. [FKP1,FKP2] which have tried to relax the above assumptions. In [FKP1] it is shown that under weaker (but still quite strong) assumption on the conversion function $f$ (and under some reasonable assumption on the hash function $H$) that DLP implies the security of (EC)DSA. Perhaps the security argument with the most reasonable assumptions is given in [FKP2]. There, assuming that the hash function $H$ is modelled as a random oracle, and the signer issues at most one signature per message, then EC(DSA) is unforgeable if and only if they are key-only unforgeable (this applies also to other schemes like the Russian GOST 34.14 and the Chinese SM2). It is not known if the key-only security of (EC)DSA reduces to DLP.



          So, in short, the answer would be no, not under reasonable assumptions.



          (Note however, that there are close variants of the (EC)DSA, most notably the Schnorr signature and the scheme by Brickell et al [B+] which do come with security reductions in the random oracle model. Also it is baffling why (EC)DSA is still in use since the patent on Schnorr expired in 2008.)



          [B] Brown. Generic Groups, Collision Resistance and ECDSA.



          [B+] Brickell et al. Design validations for discrete logarithm based signature schemes. PKC'00.



          [FKP1] Fersch, Kiltz and Pöttering. On the Provable Security of (EC)DSA Signatures. CCS'16.



          [FKP2] Fersch, Kiltz and Pöttering. On the One-Per-Message Unforgeability of (EC)DSA and its Variants. TCC'17.






          share|improve this answer











          $endgroup$



          (The (EC)DSA algorithm involves two functions: (i) the "conversion function" $f$, which for the case of DSA is a modulo $q$ operation and for ECDSA is the modulo $q$ operation applied to the $x$-coordinate of the input point; and (ii) $H$ a cryptographic hash function applied to the message.)



          Brown [B] showed that the DLP implies security of ECDSA in the generic group model and under idealised modelling of the conversion function $f$. The second assumption is in particular unrealistic as in (EC)DSA it is implemented by a simple modulo operation.



          There have been some recent results by Fersch et al. [FKP1,FKP2] which have tried to relax the above assumptions. In [FKP1] it is shown that under weaker (but still quite strong) assumption on the conversion function $f$ (and under some reasonable assumption on the hash function $H$) that DLP implies the security of (EC)DSA. Perhaps the security argument with the most reasonable assumptions is given in [FKP2]. There, assuming that the hash function $H$ is modelled as a random oracle, and the signer issues at most one signature per message, then EC(DSA) is unforgeable if and only if they are key-only unforgeable (this applies also to other schemes like the Russian GOST 34.14 and the Chinese SM2). It is not known if the key-only security of (EC)DSA reduces to DLP.



          So, in short, the answer would be no, not under reasonable assumptions.



          (Note however, that there are close variants of the (EC)DSA, most notably the Schnorr signature and the scheme by Brickell et al [B+] which do come with security reductions in the random oracle model. Also it is baffling why (EC)DSA is still in use since the patent on Schnorr expired in 2008.)



          [B] Brown. Generic Groups, Collision Resistance and ECDSA.



          [B+] Brickell et al. Design validations for discrete logarithm based signature schemes. PKC'00.



          [FKP1] Fersch, Kiltz and Pöttering. On the Provable Security of (EC)DSA Signatures. CCS'16.



          [FKP2] Fersch, Kiltz and Pöttering. On the One-Per-Message Unforgeability of (EC)DSA and its Variants. TCC'17.







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 7 hours ago

























          answered 8 hours ago









          Occams_TrimmerOccams_Trimmer

          1,74411119




          1,74411119












          • $begingroup$
            Your answer is better than mine was.
            $endgroup$
            – fgrieu
            8 hours ago










          • $begingroup$
            Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
            $endgroup$
            – Myria
            8 hours ago










          • $begingroup$
            That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
            $endgroup$
            – Occams_Trimmer
            8 hours ago












          • $begingroup$
            As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
            $endgroup$
            – grawity
            3 mins ago


















          • $begingroup$
            Your answer is better than mine was.
            $endgroup$
            – fgrieu
            8 hours ago










          • $begingroup$
            Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
            $endgroup$
            – Myria
            8 hours ago










          • $begingroup$
            That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
            $endgroup$
            – Occams_Trimmer
            8 hours ago












          • $begingroup$
            As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
            $endgroup$
            – grawity
            3 mins ago
















          $begingroup$
          Your answer is better than mine was.
          $endgroup$
          – fgrieu
          8 hours ago




          $begingroup$
          Your answer is better than mine was.
          $endgroup$
          – fgrieu
          8 hours ago












          $begingroup$
          Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
          $endgroup$
          – Myria
          8 hours ago




          $begingroup$
          Based on context, $f$ is the reduction of the group operation $g^k$ interpreted as an integer, taken modulo $q$?
          $endgroup$
          – Myria
          8 hours ago












          $begingroup$
          That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
          $endgroup$
          – Occams_Trimmer
          8 hours ago






          $begingroup$
          That's correct, and $H$ is the hash function applied to the message. I'll add it to the answer.
          $endgroup$
          – Occams_Trimmer
          8 hours ago














          $begingroup$
          As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
          $endgroup$
          – grawity
          3 mins ago




          $begingroup$
          As I'm always confused about this bit, what's the relationship of EdDSA to the (EC)DSA answer?
          $endgroup$
          – grawity
          3 mins ago


















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