If the reports about her father being an "Indian" is true, and it is recorded in her birth cert and his IC that he is an "Indian", I have no doubts her IC would reflect her as being an "Indian".
In the eyes of the Malays though, "being Malay" is more of a "social "/"religious" issue than a "legal" issue of what is recorded in their ICs. As a young girl, she may like other young "Malays" who upon receiving their ICs for the first time, be puzzled as to why their ICs record them as being "Indians", etc when they have been living their lives as "Malays" all along.
The perjorative DKK / DKA (Darah Keturunan Keling / Darah Keturunan Arab) was more of an early 1940s /1950s thing. Now, a person of different ethnicity be it Chinese, Indian, Eurasian, etc is accepted to have "masuk Melayu" ("entered Malay") and hence is accepted as being a "Malay" after "complete" assimilation. This means these "masuk Melayus" have Malay names, speak Malay, marry Malays/Muslims, adopt Malay culture and customs (clothing, food, culture, etc) and most important of all, are Muslims.
I have not checked what the PE criteria for being a "Malay" is. But for all intents and purposes, Halimah is a "Malay". She fits the "social"/"religious" definition of a Malay. Most importantly, she is accepted by the Malays as being a "Malay" just as the Malays in Malaysia accept Mahatir Mohammad as a "Malay" even though his dad's ancestors were from Kerala, India; and their acceptance of Abdullah Badawi as a "Malay" even though his grandmother (maternal) was a Hainanese Chinese.
